Update Services are tools you can use to let other people know you've updated your blog. WordPress automatically notifies popular Update Services that you've updated your blog by sending a XML-RPC ping each time you create or update a post. In turn, Update Services process the ping and updates their proprietary indices with your update. Now people browsing sites like Technorati or Sphere can find your most recent posts!
So why would you want to be on these sites? One word: traffic. Blogrolling scripts like blogrolling.com and WordPress check update services to see if you've updated and then shows it on everyone's site -- usually by moving you to the top of people's blogrolling list or putting a recently updated indicator by your link. Services like Technorati spider your links to track who links to you and who you link to; almost in real time. If you show up on someone's Technorati link list (often called an "egorati search") they're likely to visit your site to see what you said, increasing your exposure. Other sites like weblogs.com and blo.gs list recently updated blogs. Lots of people browse these when they're bored. Many of the services offer their own forms for pinging their own service, but keeping track of all those services is a hassle.
WordPress makes this easy for you by listing Ping-O-Matic's server (rpc.pingomatic.com) by default. All you need to do is sit back and let it work for you!
Certain web hosts - particularly free ones - disable the PHP functions used to alert update services. If your web host prevents pings, you should stop WordPress from attempting to ping and consider using the Feedburner Pingshot service.
http://rpc.pingomatic.com http://rpc.twingly.com http://api.feedster.com/ping http://api.moreover.com/RPC2 http://api.moreover.com/ping http://www.blogdigger.com/RPC2 http://www.blogshares.com/rpc.php http://www.blogsnow.com/ping http://www.blogstreet.com/xrbin/xmlrpc.cgi http://bulkfeeds.net/rpc http://www.newsisfree.com/xmlrpctest.php http://ping.blo.gs/ http://ping.feedburner.com http://ping.syndic8.com/xmlrpc.php http://ping.weblogalot.com/rpc.php http://rpc.blogrolling.com/pinger/ http://rpc.technorati.com/rpc/ping http://rpc.weblogs.com/RPC2 http://www.feedsubmitter.com http://blo.gs/ping.php http://www.pingerati.net http://www.pingmyblog.com http://geourl.org/ping http://ipings.com http://www.weblogalot.com/ping
By default, editing the Ping Services for a WordPress Multisite network site is disabled. This can be re-enabled with a plugin such as the Activate Update Services plugin.