Erik is right on the money here:

VoIP Magazine writer Bryan Richard has a lot to say about Skype. I happen to think Skype is a good thing for VoIP in general as it increases awareness and brings more attention to the softphone. I also firmly beleive that Skype will either adopt SIP [by partnership or other] or be a smaller VoIP player in the near future. Proprietary protocols will never make it long term when there are good open standard alternatives out there.

To say that Skype is a SIP killer is pure garbage.