i have to concur with void - an extra 24 hrs won't cut it as most people don't have the time to just map whenever.
i myself was actually heavily depending on today to do major work on my map...
if the problem is still present over this weekend too, well that's gonna really put things in a bind...
edit: oh also, for me the problem is that the orthogonal view windows are blank (with the occasional model showing up), and selection boxs in the 3d window are black instead of yellow (not a biggy there). - so that kinda means brush manipulation is impossible for me currently. this applies to new map files and old map files. (if it was the 3d view that was messed up for me like it is for grim, i'd still be able to work on the brushwork, and leave the texturing for later...
)
oh also, i had this problem before the tf2 update was DL'd. i noticed that the update was in "paused" mode or something, so i thought that if i closed down hammer/sdk and made it finish the upate, that that would fix the issue, but no luck