Turns out I don't really need to. Technorati's done it for me here, at least for the blogosphere.
Newsweek, via MSNBC, has a fairly lengthy article on newly leaked memos. This passage regarding their authenticity is interesting:
Smith told NEWSWEEK that nobody in the British government has disputed their authenticity, and he was even threatened last year with criminal investigation for violating Britain’s Official Secrets Act.Smith is the news reporter who first obtained the memos.
At this point, I would very much like to know what American memos exist from Blair's meeting with the Bush administration.