Let me add my experience to the conversation. I bought my Palm Pre on day one, and I have two other lines on my account. One, my question is which line is considered my "primary line". The other question is about the upgrade. So I'm a Premier Customer. I emailed Sprint asking them the same question and got this:
" ... The term "primary line" only refers to phone lines on a shared (or
family) plan. All three of your lines are on individual plans. However,
regardless of the plans on your account, phone line XXXXXXXXXX remains
eligible for the full $150.00 instant rebate on upgrading the phone on
that account on June 1, 2010 ..."
I may go the Best Buy route or use telesales or go to the Sprint store and pick it up. We have a pretty big one in downtown Chicago. I haven't had a rebate issue that Sprint hasn't resolved quickly, but I do have a Best Buy very close to my job. I'll go by and see if their taking reservations. The REAL question is will this guarantee me a phone? If they have 30 reservations and the store only gets 10 phones, then what? They probably don't know how many phones they'll have on 6/4.