Sorry if this is old news, but I stumbled across this and it works very well (on my 2009 MBP at least). We all know how annoying it is to have to log out when switching between your 2 GPUs. This nifty add-on appears in your toolbar along with growl, Airport etc. and lets you switch between the 9400M and 9600M cards on the fly.
It's free, works well and I have had no issues with it so far.
http://codykrieger.com/gfxCardStatus/
It's free, works well and I have had no issues with it so far.
http://codykrieger.com/gfxCardStatus/