We’ve received a few inquiries lately asking if a blogging tool exists that a) lives as as an application on your desktop and b) supports creating content and editing while you are offline.
The answer is yes, and Microsoft Live Writer (free to download) is one such tool. It supports blogs hosted on WordPress.com as well as self-hosted WordPress.org blogs. Lots more info here, and you can download it here.
On the Mac OS X platform, Marsedit ($29.95 with a free 30 day trial ) is another great option with lots of capabilities.
So how do these tools communicate with WordPress? They use XML-RPC, a cool technology that allows things that aren’t WordPress to talk to your blog. When Flickr or Youtube posts to your blog, or you use a desktop blogging client they use XML-RPC.