I suspect the announcement is coming within the next month...

Why you might ask?

I was all set to order a n810 from Amazon last Friday. I loaded it up in my shipping cart but didn't get it ordered.

Then, on Monday, I logged in to my account and noticed that Amazon has dropped the n810 from its direct sale inventory. There are plenty of resellers offering it on Amazon.com, but Amazon pulled it.

The only reason I can think of that they would do that is to avoid 500 returns from n810 purchases made in the 30 days leading up to an announcement!!

And this lines up with the release of the beta software and the mysteriously absent continuation of the SDK development time line.