Beta 7 has a rather annoying bug where if you repeatedly open and close the left-click-hold menus on the back and forward buttons, you can make the browser crash (right-clicking is okay). It took a little while to track down the problem, but it is fixed now in the internal tree. This is serious enough that we will insert a beta 8 instead of going to beta 9 as previously planned so that this fix gets rolled out also.
Also, new TenFourFox-specific branding is mostly complete and a new partial livery will accompany beta 8, along with portions of the infrastructure (similar to Classilla's custom user-support infrastructure). There will also be basic support for update checking -- while I do not plan in the near future to duplicate completely Mozilla's automatic update deployment framework, it will check for updates automatically, and facilitate you downloading them manually. Likely we will enable Sparkle-style updates when we leave source parity.
Mozilla is planning to release beta 8 by the end of November and it appears that they will be pretty close to this milestone, so you can expect TenFourFox beta 8 to emerge around the same time.