Sony has stated that they're keen to avoid the mistakes they made with the PlayStation Portable when the PlayStation Vita launches, so they're marketing it primarily as a gaming device.
"I think with PSP we tried to position it as a rather broad multimedia device," said Jim Ryan, the president of Sony Computer Entertainment Europe. "We talked a lot in the early days of PSP about its video playback functionality its use as a music device and a host of other multimedia functionality that it had."
Ryan also commented on the fact that consumers didn't appreciate the ports of PS2 and PS3 games to the PSP, as they preferred to just play them on the original system instead. With the Vita, they want to make all of the experiences "unique and differentiated".
Source: Official PlayStation Magazine