The reason the tech sites keep getting the dates "wrong" is because they can only report what they hear on the grapevine and via their official sources. But if HTC or Verizon decides to change plans after the fact, that's not the tech blogs' fault. I'm sure Best Buy was told they could sell on the 14th, but then had the rug pulled out from under them by VZW and there's nothing they or the blogs could do about it
Today's latest rumor is that the TB is, indeed, ready and being shipped to stores nationwide, but that the network has some undisclosed issue that needs to be fixed first.
This would explain why the TB seems so close, but has not yet been officially announced. If they announce the 24th, but miss it due to the network error still being in play, then customers would all start breathing into a paper bag. On the flip side, if they decide to push it back and announce the TB for, say, Mar 17 (but then the network issue is fixed right after that) then they would lose a ton of customers to the Atrix, et al and be forced to sit on their hands with a ready product
The hardware seems ready; stores are receiving shipments, and we've seen several working demos online. At this point, it seems Verizon is trying to fix something on their end and can't officially announce anything until they fix it. Hence the lack of announcement