I've just released version 2.0.1 of SimpleLog, which should, once and for all, fix all problems with rake that were caused in yesterday's release. It was a bumpy road, but I've finally knocked out all the little issues caused by a bad frozen Rails copy and a missing dir in vendor.
I'm really sorry for the trouble. If you've downloaded version 2.0, please download this new version. You should find it trouble free, and I promise, it's really worth trying out.
Thanks to everyone who sent in initial bug reports and helped me solve the problem.