I can attest that chaining Sky.FM-->SlimServer-->LiquidSoap-as-a-player works very nicely. Even the metadata being passed across from Sky.FM is handled properly, and neither processor got below 95% idle on the dual core, even with all of the other crap I run on the box (SageTV, fetchmail, etc.). That's saying a lot as it appears that both Slimserver and (possibly) LiquidSoap are doing a bit of transcoding on the fly. The one drawback to this so far is SlimServer's built-in delay (5 or so seconds). I'll need to read up on that.
It's obvious that simulcasting (rebroadcasting/redirecting) a stream is going to be simple. I need to play with the mixing features now (think "periodic jingles" mixed into an open conference call). If I can come up with an interface to Asterisk, you can consider me as having thrown IDJC in the round file.
Oh! If anyone's interested (and for my own notes), the syntax is