It seems that the next Patch Tuesday will bring some major-ish updates to Vista (unofficial versions of which are available here). Just don't call them a "service pack" — Microsoft is getting vaguer and vaguer on the SP1 issue.
All we know for now is that "a beta will be made available sometime this year", which is a far cry from SP1 coming out this year in its entirety. We're not the only ones who thought that would be the case — Intel itself was under the same impression, as was Dell. They, like us, must be thrilled.