Got about midday.
Found the two X builds nor the EGCS that I had set building over night (over morning?) had built. And I hadn't slept well either. Bummer. EGCS seems to complain about a problem with the definition of RUSAGE something - and this seems to be kernel version dependent.
Got two different failure modes for X with DRI; either X segs internally, or I get a kernel oops in the drm_release code. Great.
Found a way to hang 2.3.99-pre2-5 - open the Gnome window manager configuration. Really odd - it seems pretty stable other than that......
After those hangs, it came to me that I should be using a journalling fs; waiting for a 34GB drive to fsck is just painful.