Wrote to support regarding any WM 6.5 developments, and received this reply:
Thanks very much for writing.
Each version of Pandora software for a portable device needs to be separately developed and approved by the cell carrier. Every phone model is different, even when they run the same operating system. We're currently working to bring Pandora to more devices running on Windows Mobile.
I don't know exactly when it will be available for your model but I would encourage you to stay tuned to our "On the Go" page for updates:
www.pandora.com/on-the-go for updates.
Thanks for listening in the meantime!
cheers-
Tom K@ Pandora
Looks like 6.5 users will have to wait.