Fluid has been released and is available for download on XBL. A post on the Radiangames website says that an update should be expected in a week or two to fix a problem with some wording:
Like my previous games, I will be updating Fluid at some point, likely in a week or two. The main reason for this is a problem with the message describing how to unlock the extreme levels. In game, it says “All Silvers to Unlock Extreme Levels”, but it really should say “All 3+ Stars to Unlock Extreme Levels”. In other words, get 3 or more stars on the first 30 levels to unlock the 5 extreme levels. Sorry for the confusion!
Also, Radiangames is giving away free copies of Fluid on twitter. Follow @radiangames if you’re interested in getting a free copy. There may be some giveaways on Facebook as well, but thats not guaranteed.