A few weeks ago I started using the London cycle hire scheme, aka 'Boris Bikes'. My journey to work previously included a 15 minute journey underground from Victoria to Embankment, but now I do it overground on a bike which is considerably more enjoyable (provided you don't mind cycling in heavy traffic) as well as having some health benefits. The bikes are freaking heavy and only have 3 gears so you can't exactly go supersonic, but it's a cheap and more convenient alternative than bringing in a folding bike on the train. At the time of writing this, there are 4 location aware apps in the Market that can help you find nearby bike hire locations and see how many bikes and docks are available. Clearly this can save some wasted trips to docks with no bikes, or no slots to park your bike. I've been test driving these apps and here is my take on them.
1. Cycle Hire Widget - Market Link
This is quite a cool little app, despite the name there is more to it than just a widget. The widget hides under a homescreen icon of an Android riding a bike. When tapped, it reveals the directions of the 3 nearest docks, colour coded, the colours showing whether you can get a bike or a slot at the locations. This is very handy if you know your way around and can know which 3 docks it's pointing to.

Home screen widget, map view, and list view
You can also view the docks in a list view, which is a relief as waiting for a) the map to build and b) the location/gps lock can be a bit tedious. I also discovered you can add docks to a list of favorites, if you pay for the premium version. I will probably do this as I am quite a fan. In terms of looks and usability, it rates quite high. The interface is obvious and easy to use. The dock data also seems to be accurate and up to date.
2. SpotCycle - Market Link
I quite like SpotCycle, this is the one I've ended up using the most over the last few weeks, mostly because of the favorite docks lists. I guess most people in the cycle scheme are like me and visit the same docks every day. I've found going to a list of these is always going to be quicker than opening a map view, waiting for the map data to load, waiting for location and GPS lock, etc. I have to admit though, I had to spend some time to figure out how to create the groups for storing favorites. Those options are hidden away in a place where you don't expect.

SpotCycle: Favorites and Map views
The map view is pretty decent, it shows you circles of varying sizes and shades of red, to denote availability of bikes or docks. The data has always been up to date with this app, I've never turned up and been completely surprised at how wrong it was. A few criticisms: sometimes it stays on the splash screen for an unacceptable long time. Not sure what it's busy doing, maybe getting location data or refreshing the lists, but it's quite annoying. It also frequently says "Can't get cities list, make sure you are connected to the Internet" - well, it's a smartphone, I am always connected to the Internet! Another annoyance is it throws errors into the notification area when it can't update the dock data, to be honest I don't really want to see those. I would prefer it if could just try again later and keep quiet about it. Over all I like it though, it's very configurable and despite annoyances it's reliable, and offers a lot of features. Being able to keep lists of favorites is a big win.
3. London Cycle Hire Live - Market Link
Your mileage may vary, but I didn't really have success with this app. It only has 2 stars in the Market which I guess is a fairly accurate measure of it's quality. It worked sometimes, but usually crashed with the error in the screenshot below. I have had apps Force Close on me before, but never seen anything like this.

Holy crap.
This may be worth coming back to if the dev is still working on it, I didn't spend much more time checking it out though.
4. Boris Bikes Live - Market Link
I like the eye-catching icon of our beloved Mayor of London riding the bike, but sadly you don't get a good first impression when you open this app. The landing screen is ugly as hell, the icons are lousy. Putting its initial appearance to one side though, the functionality should be pretty good. It basically offers a map, a list of docks ordered by proximity, list of favorites, and a timer (which is not yet implemented) so you can keep an eye on your journey times (because journeys that take less than 30 minutes are free). The presentation in the rest of the app is fine, and from the list views you can select a dock and get directions to it.

Boris Bikes Live. It's got a nice icon.
With those functions it should really tick the boxes, but I seem to have issues with the bike data being out of date. The last thing you need to to turn up to dock your bike and unexpectedly find all the slots are taken. The update interval is not configurable so I don't think there's much that can be done about it. For that reason and because of the lack of aesthetics, I kept falling back to SpotCycle.
5. London Cycle Hire - Market Link
This is a paid for app. It's only £1.50 but to be honest is not really worth it. Although it's quite well presented, it really just consists of a map with the docks overlayed over the top, but they aren't colour coded or anything like that so at a glance you really can't see any helpful data apart from the location. Clicking on the dock locations then shows you the live data and a button which plots a route there from your current location.

More of the same, but more expensive.
I emailed the dev and they said they are actively working on this app and they intend to release an updated version which has user maintained lists. Until then I guess I will use something else.
Conclusion
My testing is by no means exhaustive, but so far I reckon SpotCycle and Cycle Hire Widget are the best. Cycle Hire Widget probably has an easier to use interface, but once you have SpotCycle set up with your favorite groups, you will rarely need to use anything else.