Speakeasy, a Seattle based voice over ip services provider has announced a new ‘integrated’ offering which appears to allow the connection of existing telephony infrastructure (analog & digital) including PBXs to their network.
The advantage of the concept is that keeping your old hardware in place and just hooking it up to Speakeasy’s SIP based network will save significant expenditure on hardware procurement. It’s not a particularly new approach to the problem of voip deployment in the sense that analog to voip converters have been around since the first days of voip but the offering of an integrated product with support for fairly-large existing PBXs certainly is.
That’s all assuming I understood their press release correctly 
Speakeasy press release: http://www.speakeasy.net/press/pr/pr030209b.php