The CEO of Gizmo5 Michael Robertson has responded to last week's announcement of Skype for SIP by posting a comparison (see below) of the new service and his own company's OpenSky.
While welcoming Skype's initiative, he described it as a "vaporware announcement" with "murky pricing details".

Skype and Digium, creator and primary developer of Asterisk, the open source telephony platform, have announced the beta version of Skype For Asterisk.
The move will allow the integration of Skype functionality into Digium’s Asterisk software and enable customers to make, receive and transfer Skype calls from within their Asterisk phone systems.