As far as I know, it’s coming in June, most likely with WWDC (June 8–13). Version 2.0.
My bets are June 9.
There may be incremental updates before then, bug fixes & such, but the big update will be in June.
what will the June update include
Here is the March 6 event that explains what will be in the update. http://www.apple.com/quicktime/qtv/iphoneroadmap/