As the title says Dawnguard for sale on Steam. Can't speak for the Play Station folks.

Your a day late and a dollar short on that news.

There's probably already 3-4 other threads just like this one on (previously) on the General forums alone. Next time, please put a thread like this in the Dawnguard Forums.

Does this mean patch 1.7 is up for the 360, too, then? I haven't had a chance to load up Skyrim tonight... and I was under the impression the two were going to be released together.

They would have made an announcement. Check the twitter or facebook.