A more complete list is included below. We consider 1.8 to be more stable then 1.6.

* Implement Virtual Kernel support and add a VKERNEL target. Virtual kernels are run as userland processes and provide a complete (minus hardware drivers) working kernel environment. A simulated disk driver is included and a simulated network driver using the TAP interface is included, allowing network access. See the vkernel(7) manual page for more information.
* Jails are now IPv6 aware and support multiple IP addresses.
* Bridging support has been greatly improved.
* Many, many new network drivers and chipsets have been added.
* Major infrastructure for 802.x wireless support added (WPA, TX rate control, major API layer for all wireless network devices, better ifconfig integration, and more).
* The cpdup program has been greatly enhanced and now supports remote copies via ssh.
* Introduce getcontext(3), setcontext(3), and friends
* Improved support for old-style disklabels.
* Kernel sources are now included on release CDs.
* Major rewrite of the vnode operations infrastructure, greatly simplifying the layer.
* Fix a bug related to POSIX locking.
* Tons of documentation updates and code readability cleanups.
* Restructure the kernel build to accomodate multiple architectures. Start separting platform components from cpu components.
* Synchronize a bunch of AMD64 related items (but we don't support 64 bit mode yet).
* Major rewrite of the mount glue infrastructure and NULLFS which allows the namecache topology to be shared for multiple NULLFS mounts and also allows arbitrary stacking of read-only and read-write NULLFS mounts with basically zero kernel overhead.
* Unconditionally associate a namecache reference with all file descriptors, allowing us to share vnodes across different mounts (NULLFS).
* NULLFS mounts may now be arbitrarily stacked and distinct paths are no longer required.
* Properly dereference mount point roots when unmounting. Raise hell if unmounting a filesystem which still has references.
* Do a massive reorganization of the device operations vector and remove many instances where devops functions were dependant on the calling process or thread to obtain cred information.
* Do a run through of all system header files to make sure they include any dependancies themselves, instead of requiring the originating source file to include the dependancies first. This greatly reduces the effort required to use kernel header files in new sources.
* Synchronize MII support with NetBSD and OpenBSD, including adding standard conforming GMII support. Er. In otherwords, improve driver support for physical network interfaces (phys's).
* Remove VOP locking vectors. Make VOP locking functions direct calls (and thus mandatory).
* Control access to vnode ref count fields with a spinlock
* Fix a dubious construct in usr.bin/tail (no, really! That's what the commit message said!).
* Add support for %j to the kernel printf.
* Major symbol separation for most kernel functions which inexactly mimic libc functions. e.g. printf -> kprintf, in order to allow user-mode kernels to be linked against libc.
* Update to sendmail to 8.13.8.
* Update to OpenSSL to 0.9.8d
* Update to OpenSSH 4.5p1
* Update to Bind 9.3.2-P1
* Update to less 3.9.4
* Update to awk 20050424
* Update to file 4.19
* Update to tcpdump 3.9.5
* Update to libpcap 0.9.5
* Synchronize m4 with FreeBSD
* Import libarchive
* Import bsdtar 1.3.1 and make bsdtar our default tar. GNU tar is still installed as gtar.
* Import NetBSD's ftp client under its new name (tnftp).
* Bring in GCC-4.1 (setenv CCVER GCC41 to use).
* Significant code cleanups to make the world and kernel compile under GCC-4.1. Note that the default compiler is still GCC 3.4 (GCC-4.x will probably become the default sometime in 2007).
* More work on LWP/THREAD/PROC separation for 1:1 threading support.
* Fix a major bug in /bin/make that can cause make (or some child make in a large build) to ignore ^C. make temporarily installs SIG_IGN when polling whether a signal is being ignored or not. Fix the code to not do this.
* Fix a long standing signal/fork race that could cause a process group signal to not make it to a newly fork child if it occurs while the fork is in progress.
* Synchronize the zoneinfo database with tzdata2006p.
* Add an ECC detection device, currently supporting AMD64's memory controller.
* Greatly reduce the memory allocated by fsck when fscking filesytems with a huge number of directories (primarily mirors with lots of hardlinked files). Otherwise fsck can run out of memory on such filesystems.
* Adjust RCNG to support 'blah=YES/NO' as well as 'blah_enable=YES/NO', giving us better compatibility with PkgSrc based RC scripts.
* Fix a bug related to ALTQ when setting the algorithm for a queue on which packets are already present.
* Do a major clean up of the BUSDMA header file architecture.
* We have a new web site layout!
* Use spinlocks in the objcache instead of tokens (the critical path is still lockless).
* Replace the global VM page hash table with a per-VM-object Red-Black tree.
* A considerable amount of work on IPSEC support has been done.
* NATA has been ported from FreeBSD and is currently being tested.
* Sync USB support with FreeBSD6 - use task queues to handle operations that cannot be handled from an interrupt thread.
* Explore low-speed USB busses during cold boot so the USB keyboard starts working earlier in the boot sequence.
* Start introducing glue for the SYSLINK and CCMS infrastructures. (system link protocol and cache coherency management subsystems).
* Introduce a system call skeleton and test code for SYSLINK.
* Introduce the algorithm and structural topology that will be used for cache coherency into the VFS path.
* Introduce a user-managed virtuallized page table infrastructure which can be accessed via mmap(), as part of the infrastructure to support virtual kernels running in userland (MAP_VPAGETABLE).
* Introduce vmspace_*() system calls which allows a user process to manage and control multiple VM spaces, as part of the virtualization support effort.