I haven't tried it yet. But according to:
http://forums.worldofwarcraft.com/th...43452638&sid=1

will cause a switch
/usetalents 1 (for primary)
and
/usetalents 2 (for secondary)

The bottom part of post talks about gear changing but I think they removed that from live version. I think they said they didn't like how the gear manager worked and wanted to delay release of that. I may be wrong on this point.