Okay, here is T-Mobile's official response to the "when" question:
Dear Keith,
Thank you for taking the time to contact T-Mobile. We can understand how important it might be for you to install latest version of Blackberry Software on your device and we would be more than happy to assist you with this process.
There is indeed a future OS update already in the planning stages for T-Mobile Blackberry but the time for release is not known.
We appreciate your patience and apologize for any inconvenience.
A good web site to check out is:
RIM Public Technical Knowledgebase at (url deleted, not enough posts yet).
If you have any other questions or concerns, please do not hesitate to contact us again by replying to this email or by calling 1-800-937-8997 from a landline (611 from your handset). You may also wish to try finding an answer to your question on the T-Mobile web site at (url deleted, not enough posts yet).
Thank you for choosing T-Mobile.
Sincerely,
Talal J, Rep ID 2745453
Technical Care Specialist
T-Mobile USA