It’s hard to say whether this is hugely interesting or totally irrelevant. I mean of course Microsoft’s next browser would have RSS integration. Can you imagine the uproar if they left it out? Even so, the geeks at Gnomedex seem to be foaming over this.
Microsoft seem to be playing nice by releasing their extensions to RSS under a Creative Commons license. I guess they have to release the extensions to the public so that there is uptake, and they’re not going to touch the GPL with a 10 foot pole.