It's possible an SDK version will be out sooner rather than later, but until there is a source code available, it's probably gonna be nothing more than a "teaser". (In other words, not necessarily stable enough to run as a daily driver).
Tough to say if TB will ever get an "official" ICS release, but I wouldn't hold my breath.
If I was to wager a guess, I'd say it will be AT LEAST until early 2012 before we'll start to see usable ICS releases for Thunderbolt.