While Vimeo has been available on the iPhone for the last ten months for selected videos, yesterday the video sharing website announced a new "Universal Player" which allows you to watch embedded Vimeo videos from any device, no iPhone app or Flash installation required.
The Universal Player detects what sort of device you're using, then delivers the "optimum player" to render video on your device: A mobile player for Android and iPhone, and full-fledged H.264 video to HTML5 devices such as your desktop or tablet.
Why did it take Vimeo so long to implement something like Universal Player? As Andrew Pile at Vimeo posted to the company's blog, "While it was relatively easy to build an HTML5 player that worked on Vimeo.com, making an experience that could live and work anywhere is actually a big undertaking. For example, we had to write several new video players to replace what used to be just one: behind the scenes there is a new Flash player, new Flash mobile player, new iPad player, new iPhone player and new HTML5 player. And we expect to add more."
However, not all videos are compatible with the mobile player, and you need to have a Vimeo Plus account to view non-HD videos on your mobile device.