I've just installed 10.2.4 on an eMac 700mhz combo drive model, and the problems started almost immediately.
Entourage in particular, cannot write to a keychain, or properly access the passwords within them (constantly asks for the password, even after the option to save in keychain is checked). Chimera has the same problems with the keychain, I have yet to test out other apps that use it, but I imagine the problems are all the same.
Within the keychain access app, I'm not even able to unlock my old keychain (doesn't even give me the option).
I've heard other people having major problems with this system doing a fresh install of 10.2 and then using the combo updater, and having all problems solved.
Given that NONE of these issues were present with 10.2.3, could this perhaps be a problem with the specific update from 10.2.3 to 10.2.4?
-timmerman