Actually, they paid the stockholders $620 million, but yes. Even for two studios that's a pretty significant chunk of cash. MTV only paid $175 million for Harmonix, which was the other most notable recent developer purchase (aside from Bizarre Creations being bought by Activision a few weeks ago, but I don't think the specific sum was ever disclosed in that one).
Now, despite the obvious outcry from everyone on the Internet, I'm going to say that this could not turn out horribly. EA has recently gotten a lot better about funding ambitious projects and not rushing their development, and their new CEO has (so far, at least) made good on his promise that EA would not continue to churn out a steady stream of mediocre, derivative crap.
Something that I did NOT get correct in my first post is that Mass Effect is in fact a Bioware original IP that they owned, so that goes to EA now. Which means that although the current game is almost positively sealed up in an exclusive deal with Microsoft, the two planned sequels could in fact go multiplatform in the future. This also nets EA the rights to Jade Empire (provided they wanted to do that again, which I find doubtful considering it's largely considered Bioware's worst game to date), as well as the MMO Bioware's second studio in Texas is working on. The conference call specifically mentioned that of the 10 projects currently in development between Pandemic and Bioware, EA will own the rights to 6. We only know what four of those are directly (Mass Effect, the Bioware MMO, and Mercenaries and Saboteur from Pandemic), but the only other project I know of that either studio is working on is the DS Sonic RPG that Bioware is making for Sega. So the other 5 projects (2 of which EA now owns, apparently) are either unannounced or games I don't know about. Also, EA did mention that they own the rights to Neverwinter Nights now, so perhaps one of the unannounced projects is NWN3?
This acquisition does make a lot of sense for EA. They had no real competition in the Western-style RPG market (and Japan is notoriously hostile to any newcomers on the Eastern front), and Bioware is without question the premiere Western RPG developer, especially since Bethesda has a publishing deal with 2K for Elder Scrolls.
Other bits of information I thought were interesting: Both Bioware and Pandemic are apparently working on Wii and DS games (or at least, they are planning on branching out to those platforms in the near future), and the Mass Effect dialog engine is apparently adaptable to other games and was not an alteration of the Unreal Engine 3 code. Maybe Bioware could license that out themselves for all we know. As negative as this news seems on the surface, the potential for a Super Mario RPG developed for the Wii by Bioware nearly mitigates it all for me.