To quote: This release contains the new online plugin repository. Still there are no other plugins that previously available but we will hopefully see some new plugins coming in shortly.
On top of this the new release also includes translations of Showtime to:
Starting from 3.1.126 Showtime now support "real" plugins.
By "real" plugins I mean plugins that can be loaded and installed from an online repository.
This allows third party plugin developers to rapidly develop plugins and make them available to the general public.
It's also possible to copy a plugin (which is just a .zip-file) onto a filesystem that Showtime can access and then just install the plugin from Showtime itself.
I've also started to write some documentation for how to develop plugins.
Stay tuned for more PS3 Hacks and PS3 CFW news, follow us on Twitter and be sure to drop by the PS3 Hacks and PS3 Custom Firmware Forums for the latest PlayStation 3 scene updates and homebrew releases!
MKV DOES in fact play, the resolution and video quality itself is near perfect, if not perfect. But the rendering speed is quite slow, and the audio goes faster than the video causing it to go out of sync immediately. Also, subtitles are not supported.