Google will start by alerting 5,000 to 6,000 Webmasters, leaving messages for owners of potentially vulnerable sites in the Google Message Center,
provided as a free service as part of Webmaster Tools. If you manage a site but haven't signed up for Webmaster Tools, don't worry. The messages are saved, so you can retrieve them when you do sign
up.
Google, which provides a sample of what the messages will look like, said it will begin by testing WordPress, a specific version (2.1.1) that is known to be vulnerable to exploits. If the test goes well, the search engine says it may expand these messages to include other types of software on the Web.