Garmin looks to be developing its own ANT+ adapter for the iPhone as drawings for the device surfaced today in FCC documents, suggesting that the company is quite far along. The ANT+ wireless sensor technology is often used to track fitness data and is common in devices like heart rate monitors, sports watches, and cycling computers.
Although the documents don't reveal a whole bunch, it does suggest that Garmin is aiming to more tightly integrate its other fitness gadgets with the iPhone. The company recently launched a new sports watch called the Garmin Forerunner 910XT GPS watch as well as the Garmin Vector and Edge 200 Cycling GPS devices that target pro cyclists with advanced fitness metrics.
From the looks of the adapter, it should be compatible with the iPhone 3GS, iPhone 4, and possibly the iPhone 4S, by attaching to the bottom of those devices. Garmin will probably have to come out with a free app to work in tandem with the adapter as well.