The word is out - Sling Media is working on a Windows Mobile 6 compatible SlingPlayer Mobile player and invites users with the right device to participate into the Beta. If you have a supported Windows Mobile smartphone (like an upgraded T-Mobile Dash or a brand new T-Mobile Wing), Sling Media is currently looking for people to participate in a private Beta of the new Windows Mobile 6 compatible version of the SlingPlayer Mobile. If you would like to help Sling Media out and try the new software, just drop them an E-Mail and they will get back to you within 24 hours.
As far as I can tell you, thanks to Sling Media I had recently the chance to test the (official) Beta already. It's not final yet (otherwise it wouldn't be the Beta but the Release Candidate) but it's not too much anymore Sling Media has to solve to make it working on Windows Mobile again.
According to Sling Media, the official release of SlingPlayer Mobile for Windows Mobile 6 Standard/Smartphone and Professional/Pocket PC will be available in the first part of June. And yes, it's definitely worth to await it to make the coolest gadget I've seen in the past year (the Slingbox - what else) working with Windows Mobile again!
Check out Sling Media's Beta announcement (sorry - US only) for more information.
Cheers ~ Arne