More and more organizations are committing to support WebM project. Giants like Skype, Oracle are already part of the long list of supporters. Miro Video Converter can convert your videos to the WebM (VP8) format.
Developers of the popular open source media player VLC (VideoLAN) have released a stable release candidate of VLC 1.1.0 that supports WebM. VLC 1.1.0 RC is supposed (by the developers) to be more stable than current VLC 1.0.5.
For now only Windows builds of VLC 1.1 are available to download – you can grab either standalone version, a no-install or the installer version.
VLC 1.1.0 with WebM builds also includes web plug-ins; ActiveX for Internet Explorer 6 and higher, Netscape plug-in for Firefox, Safari, Chrome and Opera.
[Update] VLC 1.1 RC is now available to download at the VideoLAN website – Windows, Mac OS X, and source code.
Update 2 – 10/12/12: Grab VLC with WebM Support here