No -- we don't have an ETA. And you can be sure this isn't going to be in patch 2.1. But CM Nethaera recently confirmed that guild housing is still on Blizzard's agenda. Of course, she can't give us any details -- she's just letting us know they're still planning on it, and that the Blizzard team has a mountain worth of ideas and there's still only 24 hours in a day.
This is a bit different than the last official response we received on the subject, which was when Drysc told us in February that Blizzard doesn't "have any current development or plans on guild halls." But he does encourage some discussion on what a guild hall could be. And on the suggestion forums, there's extensive discussion of what players want in a guild housing solution. But what do you think Blizzard will do with the idea of guild housing when they get around to it?