And have one of the following phones:
Nokia 3588i
Samsung VI660
Sanyo VM4500
Toshiba VM4050

You may now use the built-in text messaging client in your phone instead of Short Mail. SMS in the DC Metro area went online last night.

Also, if you have any of the phones with the exception of the Nokia 3588i, and have PCS Vision, SMS is free for the life of your plan. At this time, as SMS has not been officially rolled out, I do not if there is a limit on the number of free messages you get.

And no, I don't work for Sprint.