Sorry for the delay with this next phase of the release process. The ports team has gotten the release package sets built for most of the architectures (sparc64 is still a long way off) so we have begun including the pre-built packages on the ISOs. Even a very basic post-build test turned up one latent bug in sysinstall, and once that was fixed a more extensive test (load both kde and gnome) turned up two more latent bugs. Releases are the only time sysinstall/package stuff ever gets tested so ...
The 7.0-RC1 builds have one of the three bugs fixed in them. The other two bugs aren't fatal to installs on 7.0-RC1 (they were fatal to installs on 6.3-RC2...) and we have more 7.0-RCs coming so I went ahead with making 7.0-RC1 available as-is. It's a memory leak while installing packages, as long as you have more than 512Mb of memory in the machine even installing either kde or gnome shouldn't cause you too much trouble. More than that it'll start paging which is annoying. :-) All three fixes have been put in RELENG_7_0 at this point but the 7.0-RC1 builds were done before the the second two fixes went in. The 6.3-RC2 builds for amd64, i386, and sparc64 are being re-done with the three fixes in, they should be available in a day or so.
For people updating older systems, as previously announced the release branch for 7.0 has been created in the source repository so if you want to continue along the path of testing what will be released use RELENG_7_0 for the branch tag of any cvs or c[v]sup based updates. More: http://lists.freebsd.org/pipermail/freebsd-stable/2007-December/039334.html