I haven't seen anything yet. I would at least anticipate a big "Tableau 8.0 Now Available!" banner on Tableau's website. Also, you can subscribe to the feed here to stay up-to-date with new releases: http://community.tableau.com/community/forums/release-news
The official word from Tableau: end of Q1 / end of this month.*
So... any day now....
* (Dates are subject to change)