Although other phones are not mentioned in the press release it seems likely the application will be compatible with other recent S60 devices. After all the BBC is looking to make as many devices as possible compatible with the iPlayer service.
The likely techncial requirement for streaming is the ability to play videos encoded in the H.264 format - something that all S60 3.1 phones are able to do. Downloaded videos may be a different matter given they will probably use some form of DRM (the BBC currently uses WMV DRM on the PC).
The N96 will is especially well-suited to the service thanks to its large screen, 16GB of internal memory and video optimised chip-set (hardware decoding of H.264 video).
Here's an extract from a press release:
Simon Ainslie, managing director at Nokia, said: “The Nokia N96 is going to provide a gateway to quality viewing on the move and will raise the bar for mobile screen and audio entertainment. The enormous success of iPlayer has demonstrated the desire audiences have for accessing programmes at a time and a place that suits them.”
Erik Huggers, director of future media and technology at the BBC, said: "Over the past eight months we have worked tirelessly to ensure BBC iPlayer is available on as many platforms as possible, from the PC and TV to games consoles and mobiles. "This partnership is critical to ensuring we continue to reach out to audiences wherever they are and allow them to catch-up on their favourite BBC programmes.”