"SMIL Servers" (newbie question)

Am wondering if such a thing as a "SMIL Server" exists? The idea being that a server would be invoked using RTSP or SIP, which sets up an audio and video RTP stream with the RTSP client / SIP user agent. Part of the URI could indicate a SMIL document to render e.g. 
    
    sip:smil@example.com;smildoc=http://example.com/demo.smil

The SMIL document would be rendered on the server and the resultant presentation returned in the audio and media streams. 

Am I right to assume that SMIL is not just intended for "clients"?

Thanks,

Dave