To my knowledge, there is no such thing out there yet. But there will be. A couple of companies are doing it at the client level (for Web TV) but the only source I came across that is doing it at server side middleware level is this thing called Toroid. There are not many details on the site.

There are several Internet TV companies coming up all over the world. I am sure they would want to get their hands on something like this. An Open Source IPTV middleware will help evolve and scale online video/TV to new heights.

There are a few drivers for Open Source IPTV middleware already. Several service providers are unhappy about the integration problems they face in putting together various IPTV components. Open Source will only compound those problems initially but those IPTV vendors looking to sell to Internet TV (as opposed to telco centric IPTV) companies will put interfaces into such a system. IPTV service providers are usually stuck with a small number of ecosystems that come pre-integrated with other IPTV network elements such as VoD servers and Encoders etc.