Just a quick note to let people know that the Merb community is finally starting to address the lack of good documentation on Merb. I'm personally helping out with the open source Merb Book.
A preview version can be found here: Open Source Merb Book
The source can be found here: GitHub
We've got 20 plus people working on it, and considering that it's only been up on GitHub for 12 days it's pretty amazing what we've already accomplished.
If you want to learn more about Merb you should definitely check it out.