Skype has canceled development of their WM client, and removed almost all related files from their website, as reported by WMPowerUser. The official reasoning from Skype is that the Windows Mobile version of their client simply doesn't live up to the quality of their iPhone and Symbian apps, thus they have decided to discontinue development of the software. If you've already installed the Windows Mobile version of Skype or Skype Lite, you can use it all throughout this year, though if you're a new customer, you're out of luck...

Andriod client appears to have been removed too. And it seems WMPowerUser have updated with a far more likely story:

It appears Skype has given up on trying to be an end-run around the carriers, and will now focus on making individual deals to drive the uptake of carrier data plans by end users. These users will find Skype customized and locked to their handsets, only working when they have an expensive data plan. Users on carriers without these deals will find themselves denied the ability to use Skype on their phones, data plan or not.