Of you don't want to wait for T-Mobile to push it out to you you can always download it NOW!
[ROM]RUBY_ICS_35_S_TMOUS_2.14.531.3_Radio_1.14.550L.17D C_30.78.550L.15_release - xda-developers
This was a pre release of the update that T-Mobile just anounced . Exact same build numbers and all.
Depending on your style of phone, s-off, root, or just bone stock will determined the way you upgrade.
There are instructions on post 2. Its not that hard and it will not be getting any better unless T-Mobile sends out an update. This is it! Kinda bummed since I have been using it for a few weeks now. Would always want something more :-)