When I build a the new 3.1.1 version now and choose the following in Rosetta:
Locale branch: Tags/ 3.1.1
Project 3.1 and 3.1.x
WordPress Revision: HEAD
WordPress version: 3.1.1

I end up with a 3.1.2-alpha version which obviously is not what I should be getting. Is there a way to select to get the 3.1.1 tag from SVN?