As Tim Koschuetzki points out, a preliminary version of the manual for the upcoming CakePHP 1.2 release has been posted:

This version of the manual is very much a work in progress. It is being provided as a help, not an official reference, until CakePHP 1.2 reaches a final release state. While we feel this is a great start, please realize that the information provided here may be incorrect or incomplete.

There's quite a bit there already including documentation for new functionality like the config classes and URL extensions.