Mango phones are on sale/going on sale in days. Finished ROMs have been leaked. The Marketplace is rapidly filling up with Mango-ized apps. It's blatantly obvious that it's all done bar someone flipping a switch and letting the rest of us have it.
I think unbranded will be out this week on the 15th*, then it can officially be classed as "released", and the heat for any delays after that falls on the carriers and not MS. Which is why I'm glad I debranded my phone so I'm not holding out for a carrier to get round to maybe releasing it sometime this century. Perhaps.
*If rumours are right, this gives WP7 a clear run of a month or so before the launch of the iPhone 5 with no big Android releases (hardware or software) inbetween either. MS would be nuts not to get Mango out first and give it the best shot they can.