Scans post for links, checks if they are pingeable and sends pingbacks with results returned, improves chances of successful pings!
While working on this plugin I noticed a large occurrence of the pingback fault 17: "The source URL does not contain a link to the target URL, and so cannot be used as a source." A really frustrating message given you are sending a pingback because the source DOES contain a link to the target, yes? Might I point out that very few WordPress users are aware of this even happening because nowhere does WordPress actually return you these fault codes..!
Well, after a bit of testing I found the bug seems to be in the XML RPC server code for Wordpress, specifically the strip_tags function in PHP is just not reliable enough for getting anchor links on the variety of WordPress templates out there (IMHO). (Line 3422 in WP3.1)
Unfortunately, since the bug is in the server code itself, you can't fix it on someone elses blog can you? That's why this is a workaround instead. The Pingchecker workaround will scan your post content for links using regex instead, then echo a hidden div element containing all the links (with an added nofollow tag so you aren't linking twice) in your blogs footer, which is picked up much more easily by the strip_tags function in use by the server.