From the 'time limited offers' files:

If you're running an open source Asterisk PBX and you want to integrate it with Skype, you need to move fast - the open public beta availability of Skype for Asterisk closed on August 7th.

The way I understand it is with Skype for Asterisk you could use Skype just like a normal phone line as part of the PBX which is kinda cool. It basically means you can have your own Skype based call center potentially. But unlike Asterisk which is freely available and open source Skype for Asterisk has some limitations.

"This is a "time-expiring" beta - the software will stop working on August 31. The download is also currently time-limited - it will be available until August 7 on our website," Asterisk community manager John Todd  said in a mailing list post. "After the 31st, you would need to have purchased a license for the SfA software."

Todd did not have any pricing or licensing info available to share.

Earlier this year Todd did tell me that the plan was to have AsteriskNOW 2.0 - which is an all in one Asterisk/Linux OS/GUI app - would have the Skype for Asterisk piece integrated in. Currently AsteriskNOW is at version 1.5 and it is a freely available application.

While I understand that Skype is not an open source application, it makes sense from my point of view that Skype for Asterisk be freely available for community use. Sure Skype to Skype users won't generate any revenues for Skype, but it's all the add-ons (SkypeIN, SkypeOut) that generates the money anyways and likely Asterisk users will still need those services too.

If you're looking for the public beta -it's available here until August 7th.