While the Linux 2.6.35-rc4 kernel represents three weeks of work compared to the usual one week, there aren't a plethora of changes. Linus was strict when releasing the Linux 2.6.35-rc2 and 2.6.35-rc3 kernels about not letting in non-regression fixes and so as such there wasn't a lot of new code breakage. The Linux 2.6.35-rc4 kernel though does carry some i915/Radeon DRM updates, file-system and CFQ fixes, and various other changes.
The release announcement for the Linux 2.6.35-rc4 kernel can be found as always at LKML.org. We also continue to monitor the performance of the Linux kernel on a daily basis at kernel-tracker.phoromatic.com. The Linux 2.6.35 kernel, which is going to be used by Ubuntu 10.10 and other Linux distributions updating late in the third quarter or early fourth quarter, is shaping up rather nicely and Linus doesn't expect his holiday will have pushed back the release by much.