Here’s some great news from the WordPress development blog: WordPress 3.6 is going to have built-in support for audio/video playback. You will be able to upload a media file, and WordPress will handle playback with the MediaElement.js. Shortcodes will be available, as well as template tags for theming support.
…there is now native support for Audio and Video in core! There has been great support for embeds by way of
WP_Embedand oEmbed providers for a while, but, if you wanted to play an MP3 from your Media Library, you had to install a plugin. Supporting audio and video in core gives bands, podcasters, vloggers, et al the ability to easily and beautifully expresses themselves through sounds and moving pictures without using an external service.
This should go nicely with the coming changes to Post Formats—unless the plans have change, a UI based on the one by Crowd Favorite is going to be a part of the WordPress core, hopefully making post formats actually useful. (I’ve been using the Crowd Favorite plugin on my personal blog for awhile now, and it’s great.)
Another part I find interesting is the addition of embed handlers for common media files. You will be able to paste an URL to an AAC/MP3/etc. into a post and it will be seamlessly replaced by a media player, just like how oEmbed works.
Audio / Video support in Core [Make WordPress]