SIP may have been initially motivated by telephony style applications but it
is a very general and extensible negotiation protocol - it was that aspect
that grabbed my attention when I first heard about Schulzrinne's work on it
several years ago. I think the point really is that SIP is extensible and
may be a very reasonable platform on which to build a wide range of peer to
peer and distributed application control.
SIP certainly is extensible, but I strongly suspect that we wouldn't be giving
it serious consideration for this use if there weren't already a substantial
investment in it from the telephony world. What makes sense for telephone
providers (because of that investment) doesn't necessarily make sense for the
Internet. SIP should of course be considered, but it shouldn't be assumed as
part of the solution path before the WG has even had a chance to consider
other, possibly less complex, alternatives.
Keith