http://www.kotaku.com.au/2009/11/bioware-what-weve-learned-from-bethesda-and-what-makes-us-unique/
I thought this article was sort of intriguing, apparently Dragon Age: Origins took 6 years to make. If that is indeed true then it seems ludicrous that Dragon Age 2 would be announced so soon after release of the Dragon Age: Origins. It seems unlikely that after showing off Dragon Age: Origins DLC, they would announce a sequel and if they were to announce a sequel, then why wouldn't BioWare have done so at E3 where it would have gotten a lot more media coverage then it would in Game Informer. That theory seems to apply to TES:V as well, but Bethesda seems to stick to tradition when announcing a game and therefore will announce it via Game Informer.
Sorry to burst bubbles, but I'm sure I read about this when DA:O came out -- yes they worked on it for 6 years, but they were working on the trilogy as a whole - and they said the turn around time between games would be fast as a result. I'll see if I can dig a link up to cite.
Edit:
I searched my usual blogs and could not find where I heard that. Now that I think of it, it might have been in one of the podcast interviews that Casey Hudson and other Bioware reps have done in support of the DA and ME series - I swear I read/heard something about concurrent development of the series resulting in a much shorter turn around time between sequels - but because I can't find my evidence, you can believe it or not as you want.
Second Edit:
Could be I'm confusing myself - now I wonder if the concurrent development/turnaround time thing was regarding ME2 and ME3... Pah, I've confused myself.
At any rate, I believe they could get DA:2 out quickly if they use the same basic engine; I'm sure they have all the lore and basic plotting worked out for the series, I would not be surprised really if they did hit Feb 2011.
(if they want to take a little longer so the game doesn't look so ugly, especially on consoles, that would be swell)