OP- Great post. Thanks for letting other SDers know about these cell phone service discounts almost anyone can take advantage of.
One thing to be aware of though is that adding this discount onto your existing T-Mobile plan will extend your contract or start a new 2-year contract if you are currently out of contract. This should not affect your upgrade eligibility though (e.g. if you are currently 6 months away from being eligible for a full upgrade discount, you will still be eligible to upgrade in 6 months, but this effectively extends your contract out to 2 years from the date of the plan change. If you then upgrade in 6 months, that would once again re-up your contract to the full 2-year term.)
Employer/organization member discounts on cell phone plans are a great deal that everyone should be taking advantage of, regardless of carrier, but I just wanted to make everyone aware of the contract renewal clause for T-Mobile (and I assume others, though I can't say for certain), as some people may wish to remain out of contract, or may not wish to stay with their current company for the full 2 years.