Last modified: 2009-07-17 01:09:18 UTC
The installer already sets the memory limit to 20M in LocalSettings.php if it detects something lower, but this is still insufficient for some actions (GD image thumbnailing and the unpaginated version of Special:Allmessages come to mind). I recommend bumping this up to 40M, unless there's a reason not to.
*** This bug has been marked as a duplicate of bug 16084 ***