1) Who is they? If we're talking about Nokia, no. They are not "killing" the hype. There is no difference in knowing the iPad 3 or iPhone 5 is being announced next week, next month, or next winter, after seeing a millions prototypes and parts and having to wait. It hasn't been two months since they unveiled it, and it was a prototype at an expo that consisted of many other electronics companies, so Nokia had to work to get something to show for CES on the CES calendar, and the same goes for MWC. If Nokia scheduled their own event in this quarter, yes, we'd likely know something definite. That is why Apple doesn't attend CES or MWC because they work on their own schedule.
2) If it is AT&T we're talking about, it is somewhat likely they could be dragging their feet. Nokia and AT&T have had nearly no relationship on subsidized phones or devices in the past, save for a few older Symbian phones and feature phones. AT&T hasn't carried a Nokia smartphone since the Nokia Surge, which was from 2009. If they are ready and willing to get the Lumia 900 launched, they don't appear to be so. Nothing on their website has anything, while Nokia has the full details of the device, and a sign-up to let you know when its available. I guarantee if the Lumia 900 was announced at CES as an unlocked phone first, and then later announced coming to AT&T, we'd already be seeing it. The Lumia 800 starting shipping live at the Nokia World 2011 keynote by Elop, because it started out as an unlocked device. Nokia has never been thrilled working with US carriers, because they're different than any other carrier in the world, so I can imagine Nokia is really anxious to get this ship moving, but no one can kill the hype, unless you really weren't that interested anyways or just very impatient.