When Pandora announced support for Windows Mobile, it announced that it was only available for Sprint and Verizon customers using the HTC XV6900 / Touch or Motorola Q9C devices. It promised that new devices would be added later.
Progress since then has been slow but Pandora has now added support for two new devices. On the Sprint network, you can now add the HTC Mogul to the list of supported devices. It is joined by the Samsung SCH-i760 on the Verizon side.
The Pandora client (now at version 1.1.10) can be downloaded by pointing your phone browser to www.pandora.com.