My mistake. When I checked after their announcement yesterday they had not updated their store page (http://www.sencha.com/store/touch/). Also, their license was a bit confusing to me, and I thought it was only free for those who wished to make their entire application open source.

Not according to their site. It says: "And now, we’re making it available free of charge for commercial or use under the GPL"

Yes

Edit: No. ExtJS costs money, but it looks like Sencha Touch is free for everyone, as others have noted.