(Stefan Krumnow)
I just checked-in some changes so that the project can now be build with an JDK version 1.5 (it wasn't that difficult).
(Maybe you will have to delete the folder oryx/build/buildApps/ manually before you run the build with ant under JDK 5)

One additional comment: When updating your working copy there will often occur SVN-conflicts in the oryx/ folder.
These conflicts are caused by the build-process that copies some source-files and can be resolved by using the new incoming version of the files.