Have you registered for Wrath of the Lich King's opt-in yet? You may want to soon, given that Eyonix has reported announcement at the WotLK Friend and Family Alpha forums that the expansion's Alpha phase has ended. While Eyonix's exact post is a little elusive to track down, ElGee of the deathknight.info forums managed to copy and paste the Blizzard poster's announcement:

The Wrath of the Lich King alpha test has now come to a close. We’d like to thank all of you for your participation and invaluable feedback on the game. The World of Warcraft team is hard at work preparing for the next phase of testing, and each of you will be invited back to participate. We're also happy to inform you that we will not be wiping characters as we transition from alpha to beta. However, all current alpha characters will be locked for a short period of time, allowing new players entering the beta sufficient time to catch up.

Over at the WotLK Wiki forums, demosthenes notes that a source close to the devs reported very similar details to Eyonix's announcement. A similar announcement by Blizzard poster Wryxian at the Europe forums was further confirmed saying the same as Eyonix (screenshot by azri at the deathknight.info forums):

 

So, does this mean that WotLK beta will be arriving soon? Not likely according to demosthenes' source, who indicated that even with WotLK Alpha's conclusion, beta still looked a long way off:

I think they [Blizz's development team] are rushing development to meet an arbitraray deadline; they are nowhere near ready for beta. I also think speculation about "5 new skills per class" is bunk. [I asked how many we can expect since warlocks already have 3 known] Each class will have 2 new skills, ignoring exceptions like druid ooc res. [pause] It MIGHT get bumped to 3, as there are a lot of skills that have been datamined but were never seen on alpha (like mark of divinity and air elemental) [though it is currently speculated that MoD will be a Paladin skill].

We remind the readers to take this info with a pinch of salt. As some of the readers may have noticed though, it's uncharacteristic of Blizzard to rush deadlines, given the company's "It'll be ready when it's ready" approach to game development. Could Blizzard's recent merger with Activision have something to do with this? We're not sure, though you may to stick around in case we run into any more details regarding this matter.