According to "a reliable source", the Sprint SERO (Sprint Employee Referral Offer) plan is going to cease being offered on July 10th.

The SERO plan was in my opinion the one thing that made Sprint interesting. $30 a month got you 500 minutes, unlimited data, unlimited messaging and unlimited nights/weekends. Thousands of people have joined or returned to Sprint thanks to this plan.

Sprint is replacing SERO with a much less interesting $10 discount on their cheapest "simply everything" plan. I’m not entirely sure that Sprint understands the consequences of their actions. Thankfully they’ll allow existing customers to stay grandfathered in on SERO, but any changes to the plan like picking a new phone, will require you to upgrade to the new plan ($59.99).

This is horribly poor timing by Sprint, especially with the new 3G iPhone arriving in the same week. One would think that an operator losing this many customers would do everything they can to keep people loyal to them.

Source: Sprint users forum