I hope you are referring to Interactive Digital TV. It certainly is the future of television with t-commerce and all. DVB released DVB-RCT, DVB-RCS etc for wireless return channels but none of them are largely, if any, deployed. The most common return channel is a V92 modem or a ethernet port.
As for middleware, there is the free DVB-MHP. OpenTV and Microsoft Mediaroom etc are commercialy available.
You can roll out your own middleware on Windows CE or Linux over a decent ARM/MIPS processor. Check out Conexant H.264/VC-1 decoders that pack a ton of functionality including a V92 modem, ethernet MAC, SATA ports, a 500MHz+ ARM11 processor etc.