We have been working on unifying all the manifests for easier maintenance of the code. The single manifest will support restricted builds and open builds. If you don't use the group feature it will try to sync all the repositories.
To use the repo groups support use the -g flag when you do repo init.
$ repo init -u ... -b ... -m tracking.xml -g "group1, group2,..."
There are currently 3 groups you need to be aware of:
1. common, all gits which are common
2. origen, all gits which are specific for origen
3. vexpress, all gits which are specific for vexpress
and so on ...
Getting the vexpress code (for instance):
$
repo init -u ... -b ... -m tracking.xml -g "common,<vexpress/pandaboard/galaxynexus/snowball..>"