I had mentioned a few days ago that the SoCG 2011 venue was set to change. The new venue has been announced: it's at UICP, right near the Eiffel tower (which I might add, looks like a snapshot of a negatively curved mesh). There are hotel recommendations as well, but it sounds as if even if you made reservations at a hotel near the previous location, it won't be too much trouble to get around. Aah, the joys of efficient public transport.
In any case, do those registrations now, and get those hotel rooms booked. As a former organizer, I know how nerve-wracking it can be while you wait for the registration count to climb towards respectability :).