The closest you're likely to come to this is a Bluetooth access point. AXIS, Belkin, Billionton Systems, and D-Link have all made such beasts. AXIS, Belkin, and D-Link each discontinued their models a few years ago. (And D-Link never offered theirs in the U.S. anyway.) Billionton may make theirs still, but I seem to recall reviews stating theirs was...peculiar and difficult to use somehow.

If you have problems with money (you have too much of it), SENA offers some models that appear quite nice. I'd like one, if you're buying.

The MicroBAP also looks interesting, if you're into "some assembly required" toys. It's certainly small enough to be turned into a pocketable accessory for an Internet tablet.