The 1.1.0.M1 release of Spring Social already is compatible with Twitter's 1.1 API. I'm pushing hard to cut a GA release before Twitter closes down its 1.0 API.
However, realizing that time is getting tight, I have a backup plan of cutting a 1.0.3 version of Spring Social Twitter to support Twitter's 1.1 API. Right now that work exists in a local branch on my machine, but I plan to do some testing with it next week and cutting the 1.0.3 release as soon as I'm satisfied that it works, no later than Twitter's March 5 date.
Spring Social Project Lead