Started a 2.5.55 compile today in preparation for moving kernel.org to 2.5.x and making linus eat his own dogfood.
Of course, the compile failed, so I grabbed 2.5.58 which also failed. Apparently there are fbdev includes missing in the tar file (which I did find on Linus' machine at work, but there were further issues).
After disabling fbdev, i discovered errors in the bttv driver (which i fixed) and the stradis driver (which are so extensive that I'm still in the process of fixing). I also discovered that some people don't know how to write proper gnu syntax asm and changed binutils to accept their bogus code. Fixed.
Ugh. I really wish people would report kernel code that doesn't compile to the MAINTAINER of the code rather than expecting that everyone has the time to sift through LKML looking for the random bug report.