My Polar CS200 bicycle computer is one of the few standalone gizmos my iPhone hasn't replaced yet. Hooked up wirelessly to sensors on my bike and a chest strap, the CS200 gives me data on speed, cadence, distance, pace, and heart rate during my daily rides. My current bike computer gets the job done, but I've often wished for a fuller-featured solution, especially since Polar's computers aren't able to sync with Macs without using third-party software, some of which is pretty expensive.
Patently Apple has just discovered a 2009 Apple patent which would turn an iPhone or iPod into the bike computer of my dreams. The patent shows an iPod (amusingly, the third-gen "fat nano") standing in for a bike computer and accepting the same sort of data as my current Polar computer, like speed, cadence, heart rate, and so on. But the patent also shows much more interesting features like turn-by-turn GPS, gear settings, and sharing options that would allow cyclists to communicate with one another in ways not possible with the current crop of bike computers.
It's the sharing options that are the most innovative, and they basically come across as Nike+ for bikes. With routes mapped via GPS and riding characteristics recorded via the bike's sensors, this iPod/bike pairing could allow riders to share realtime data on their rides, assign ratings to trails, and even form riding groups based on compatible fitness levels.
Some of these features are already available in limited form in iOS apps. Runkeeper is what I've been using, as it lets me record bike routes complete with speed and elevation data, and I can share those results with others -- but only after the ride's over. Integrating an iPhone or iPod with a bike's sensors and being able to provide realtime data to other cyclists is a step above anything else I've seen in this field. Not all of Apple's patents wind up as marketed devices, but I certainly hope this one does.