This doesn't jive with the timeline MS has hinted at. If 7 is going to be available by October for GA then there will not be another RC. It was posted by Sinofsky himself that RTM is 3 months away from RC release. Does this mean they haven't started work on the framework for a service pack? I think they probably have started getting the basis ready, but I don't know how you can release a service pack for something that doesn't even have any security patches or critical/recommended updates for it yet. SP1 being included with Server 2008 was different in the fact that they had already released Vista and that they were both running the same kernel. So when Server 2008 was released Vista SP1 was released too. Who knows though maybe there are some truths to these rumors but I can't seem to wrap my head around this.
I've seen no proof that build 7200 (or higher) is considered to be release candidate 2. So I'll stick to the term 'pre-RTM build' unless some can show me where Microsoft are officially referring to there being a RC2.