Haven't seen anyone post this yet, but got an unsolicited message on my EVO last night:
Called the number tonight and within a few minutes they had re-enabled the phone's ability to stream media (like the SiriusXM or Rhapsody apps) over 3G again. I don't know if this is just the same proxy correction fix that people have been doing on their own using the MSL, except being done on Sprint's end, but if you haven't gotten it fixed yet... give them a call and they'll fix it for you.
Streaming on Your HTC EVO Device
Streaming quality on your HTC EVO may be impacted by a known issue with the Sprint carrier network. To resolve this issue, please contact Sprint at 888-211-4727. Let them know that you are having trouble streaming multimedia on the HTC EVO with software version 3.70.651.1
Called the number tonight and within a few minutes they had re-enabled the phone's ability to stream media (like the SiriusXM or Rhapsody apps) over 3G again. I don't know if this is just the same proxy correction fix that people have been doing on their own using the MSL, except being done on Sprint's end, but if you haven't gotten it fixed yet... give them a call and they'll fix it for you.