Come back in about a year. Even the much hated Vista took about 14 months before a service pack was ready for it. So if we keep to that as a general schedule, come back in 2011, or at least much later this year.
And even if it came out tomorrow, it's not like the service pack would likely add any significant new functionality. They are typically just a big mass of updates, and maybe some minor new features. Don't make the mistake of thinking of service packs like a refresh of the product as a whole. Probably 95% of it is just a rollup of all the updates that have been released up to a certain point in time. Completely unremarkable, and so long as you keep your system updated via Windows Update, you are effectively beta testing SP1.