I hate to spoil a good joke, especially as Paul Thurrott has such a nice screenshot of the dialog, but the pseudo-english text showing up in the latest Vista build is less of a mystery if you read the release notes for this build. I'd rather MS got a new build out than held it over to fix something at this level - although it's also a shame to see Vista turning itself into the butt of a few more jokes at this stage of the game.
From the release notes, and indeed the email with the download link... Things you should know before installing Pseudo Localized Text Present Parts of the OS contain Pseudo-localized text, or non-english characters placed together to approximate English words. (Text that looks similar to the following: "?i?d??§ ?èðì? Þläÿ??") This is used internally, is known and being addressed in future builds.