For those of you following the CVS tree closely, be warned some huge changes have just been commited by your truly.
b2config.php is gone! CVS will try to delete yours (it should fail if you have modified it). This is replaced with a very small amount of configuration in wp-config.php. A sample file is in cvs (no more over-writing your settings). The rest of the configuration is done on the all new option screens. All these options are now stored in the database. New stuff includes default settings (category, draft, etc.) for new posts.
Unless you really like living on the bleeding edge, you would do well to wait until I have written the upgrade script for all this stuff.