It appears like the Google Webmaster Central team is testing a new verification process for Webmaster Tools.
A Google Groups thread reports finding the following data in his log file:
126.96.36.199 - - [11/Sep/2008:10:17:09 +0100] "GET / google38b4a154a92b0b4f.html HTTP/1.1" 200 - "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
188.8.131.52 - - [11/Sep/2008:10:17:09 +0100] "GET /fdfdkll.html HTTP/ 1.1" 404 - "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http:// www.google.com/bot.html)"
Googler, JohnMu, said that this is related to Google testing a new verification process:
The accesses of "/fdfdkll.html" were made by an experimental new system that is set to complement / replace the existing Webmaster Tools verification system. In the future, the requests should change to the more common "/noexist(...)" that we're used to. I'm glad to see that progress is being made on the verification system :-), thanks for bringing it up!
Google Webmaster Tool's current verification process was always been someone awkward for webmasters to get working and share with their clients. So here is hoping to a better system soon!
Forum discussion at Google Groups.