The latest snapshot has been posted with that includes some files that were missing from the earlier jQuery/jQuery-UI upgrade. Also fixed a notice that was observed with the registration process, and another error that was found when the new setup process was run with older versions of PostGIS (anything before 1.5.x, which did not have the geography_columns table).
As usual, you can get the latest code from the downloads page.
Update: the snapshot mentioned above is replaced with 20100423b - part of the problem Michalis and I were running into today stemmed from a bug in the error message being returned by the JsController when a file was not found. If this happens in the future, the error message should be more informative.