About a year ago, Google introduced the new Google Webmaster Tools API. This API allow developers to communicate with Google Webmaster Tools (GWT), without actually accessing the front end, so they can code reports, verify sites and so on, without touching the actual GWT interface.
The issue has finally be discovered and confirmed. If you try to use the PUT and DELETE request methods in the Webmaster Tools GData API, you will get a "400 Bad Request" response returned. Again, Google has confirmed the issue and hopes to get it fixed "early next week."
Jonathan Simon said in the thread:
Good news...we've tracked down the API issue and should have an fix in place early next week. Thanks for your help in getting this resolved!
Forum discussion at Google Webmaster Help.
Update: This bug was resolved on August 5, 2009.