Per customer service at 15:00 eastern today, the data "difficulties" being experienced are nationwide with multiple carriers. At this point, Sprint has no outage resolution time, and can provide no formal explanation as to the cause.
Personally, I've been able to access some select internet sites using the browser, but have not been able to use any applications which require a data connection, nor have I been able to download any new applications since I noticed the outage, about 24 hours ago.