The DAP Review gang stumbled upon on a PowerPoint slide (in Japanese) on Rio's product roadmap and it looks as if a new versions of the Rio Karma and the Nitrus are planned for Q4 of this year. The Karma 2 was previously mentioned here:
I can tell you that the Karma 2 is very small. If it keeps the form factor it had at the show it will be the most compact on the market. It will also have a color LCD and an SD expansion slot. You don't need an expansion slot for content, but it will allow swapping files on the drive. You can assume it will have a USB 2.0 interface, at least a 20GB drive, and the excellent Rio menu system, which rivals the iPod's for ease of use and clean design.