(Using 5.6U6)
I upgraded php to 4.3.6 and that caused a lot of problems for my ibays. I had to extend that basedir line to "/:/home/e-smith/ibays/ibay-name/:/tmp/:/usr/bin/:/usr/share/pear/"
I have no idea why this happened but it was a bit annoying. Pear is still causing a few problems but I can live without it for now. On the other hand, it is a more secure way of doing it as you have to more explicit in your definitions of allowable directories.