You can access the latest version by going to bbc.co.uk/mobile/iplayer/, or opening the iPlayer widget on the phone, where you will be prompted to download the latest version.
As in previous versions, content can be accessed via the channels listing, via categories or via search. When listening to a radio program or watching a TV program, the Realplayer application is automatically launched and used to play back the streaming media.
All content can be streamed and, where the digital rights are available, it can also be downloaded for later playback. If you're a 3 or Vodafone contract customer you can stream over a 3G connection. Others are obliged to use a WiFi connection.
Aside from a smoother look and style, the mobile web version of iPlayer adds an additional tab, 'Favourites', which can be used to access a list of content of user specified content (via an 'add to favourites' link) or recently played content.
Live TV is now fully integrated into the channel listings and gives access to shows that are currently being broadcast (generally with a delay of around 10 seconds).
The move away from a standalone widget is a shame, as the latter offered a more contained experience and better support for multi-tasking. However, the BBC does deserves credit for continuing to maintain an excellent on-demand mobile service. With the move to a mobile web version, it would be good to see them extend the range of supported devices (e.g. to the popular E72) - something which should be trivial given the platform similarities.
The move to the mobile web is also likely a precursor to including the social functionality that was recently added to the PC version in the mobile version of the service.