To further solidify a Spring 2011 release (and subsequently, why it makes sense), Activision/Blizzard has plugged Starcraft II and the new World of Warcraft: Cataclysm expansion for 2010 release dates.
Activision | Blizzard - Quarterly Results
What does that mean?
Cataclsym this fall, SC2 this winter, Star Wars: the Old Republic next fall.
From a strategic business standpoint, Bioware is poised to crush the market with the timing of the release of SWTOR.
Again, why am I proselytizing a fall release? Because of the timing, I see Bioware wanting to kill with this opporutnity. If anyhting has been learned about making "the next MMO", it is all about timing. A great game won't do it alone. Want a real world example? You can't release an iPhone killer 6 mos. after everybody renews their 2 yr iPhone contracts. See Google Nexus One.
Then again, I could be wrong.