There's now an installed base of a billion Bluetooth-enabled devices worldwde, according to the Bluetooth Special Interest Group (SIG).

The group also observed that 12 million enabled devices are now sold every week. Apple is an associate member of the Bluetooth SIG. The figures come from market research firm ABI Research.

To put the number in perspective, Michael Foley, Ph.D., executive director of the Bluetooth SIG, explained that one billion is greater than the number of PC users in the world and equal to the number of mobile phones shipped this year. The Bluetooth SIG estimates that two billion Bluetooth devices will ship per year starting in 2010.

"Exciting things are shaping up for Bluetooth wireless technology and with the advent of several new uses of the technology in 2007 in the home entertainment, medical and gaming arenas, I feel confident that Bluetooth technology will continue to surpass expectations," said Foley.

Mobile phones make up the bulk of Bluetooth shipment numbers, along with audio headsets. Vehicles, stereo headsets, media players, computers and mice and keyboards also contribute.

The Bluetooth SIG projects a growth in the volume of Bluetooth-equipped medical devices, gaming devices, camcorders, projectors and digital cameras in 2007, once a high-speed Bluetooth specification is released. For now, devices at the leading edge of Bluetooth transfer speeds are limited to the specifications of Bluetooth 2.0+EDR, the spec that Apple uses inside currently shipping Macs.