While I doubt the powers that be at AMD were losing sleep waiting for SiS to support the AM2 socket, this is important. SiS provides a LOT of chipsets for low and middle bracket computers. A few more wins like this and AMD can rest assured the socket won't debut into a vacuum.
I mentioned this to a local white box maker and he thought it exciting.
Evidently there was some worry about chipset availability for the new parts. That's all over now.