First off, Harlan Carvey mentions that his new book has information about this on page 205; I still haven't made it out to buy the book yet, but the day isn't over. Harlan also mentions that the file is created when IE7 is installed.
Wow, there's been quite a response to the first post. . . A couple of things that Andreas Schuster requested. This is the contents of the HKLM\System\CurrentControlSet\Services\EventLog\Internet Explorer
and this is the HKLM\System\CurrentControlSet\Services\EventLog\Internet Explorer:
This is Internet.evt opened in a hex editor:
the remainder of the file appears to be empty. Using psloglist against the file appears to dump the contents of the file.