I've started evaluating the developer kit from the very nice people at BlueCats (http://www.bluecats.com). I came across the company while researching the current state of the indoor location market, and the developer in me was attracted to the combination of their (Bluetooth LE based) beacon hardware, SDK and server side management and reporting tools.
It's early days, but the devices are nicely designed and work as advertised, and the management console looks good too. There are a few configuration issues that need to be ironed out, in conjunction with BlueCats support, but I'll hopefully be up and running soon.
It seems the SDK is iOS only, but I'm assuming you'd be able to use a free library like Radius Networks Android iBeacon Library (http://developer.radiusnetworks.com/ibeacon/android/) if you want to use the BlueCats beacons with an Android device. I look forward to testing this assumption myself.
If you're interested, you can find more information here: