Microsoft appears to have published Office 2007 and Vista keys to Select licenced customers.
Along with the keys is a download entitled "Windows Vista Enterprise English Disk Kit MVL ISO CD". It's not quite clear what this is but since the download is 2641MB you can only assume it's Windows Vista Enterprise Edition. The download was published a few hours ago.
We are currently awaiting a response from Microsoft and will update shortly.
Update: Microsoft have now pulled the download but the keys remain. Updated with screenshot of what was. A Microsoft spokesperson has confirmed that Vista has not yet RTM'd but is unable to explain the odd appearance of Vista Enterprise.