DivShare, a file host for social networks and other sites that we've covered in the past, is launching a Wordpress plugin today. This allows users of the Wordpress blog platform to upload files to DivShare straight from your "Write Post" page and put them into your post with a single click - no ftp and no code to copy and paste. Wordpress comes with an upload form, of course, but the use of DivShare means that you'll save on bandwidth bills - you can use it to upload images, MP3s, videos and the rest.
When you upload MP3s, it'll insert them into DivShare's Flash player (see DivShare's MySpace MP3 player), which offers them a bit of promotion in exchange for hosting your files. From what I can see, it also links the image to the DivShare site, as Flickr does, and offers the option to include thumbnails instead of full size images.
File hosts are basically interested in hosting as many images as possible: services like Photobucket love to boast about how many images they serve, and actively encourage developers to use their Photobucket hosting to save on bandwidth. What's more, every piece of media embedded on a blog provides a link back to the host, helping them to build traffic. I haven't seen blog plugins from Photobucket and ImageShack, and if they don't have any yet, they're missing a huge opportunity. DivShare was originally seen as yet another hosting site, but I think it could be a contender.