Similarly to Virgin Mobile, Boost has announced at CTIA this morning that it will begin offering 4G plans and handsets on May 31st. Both are no-contract MVNOs on Sprint's network, so the synchronicity is hardly surprising, and it also means that the 4G in use here will be WiMAX since Sprint's LTE rollout is not yet open to the public. Boost's plans start at $55 per month, though you'll be rewarded for making your payments on time with a bill that shrinks to $40 after 18 months. As we'd heard rumored, Boost is offering the HTC Evo Design 4G, which will set you back $299.99 upfront, and there's no word on any other options or mobile hotspots available just yet. Boost promises average upload speeds of 3Mbps-6Mbps, but while the data plan is being marketed as unlimited you'll be throttled beyond 2.5GB.

Update: Sprint has told us that the speed cap beyond 2.5GB is only on 3G data, contrary to the company's website.