As of right now, Research In Motion has confirmed that the WiFi-only version of their first tablet device, the BlackBerry PlayBook, will launch some time before the end of the first quarter, 2011. After that, a WiMax-enabled version of the tablet will launch on Sprint's network some time in the summer of this year. However, other carriers have been left out of the picture in the United States so far. That may change by March or April, if an unnamed source is to be believed. According to the source, it turns out RIM is working on releasing a 3G-enabled PlayBook for AT&T.