Google did not understand that sometimes they have to actually create and do something themselves, and not just combine open source materials and sell them as their own.
Unfortunately, there is no standardized BT 4.0. Low Energy API for Android. Maybe Google just decided to go only to NFC for Google Wallet or something else, and then let BLE die. (We really need BOTH!)
Broadcom tried to create an open source API, but somehow (perhaps Broadcom wanted to get money from them?), None of the phones included the ".so" file in its Android assembly, so this API is useless.
TI and Motorola made another API for the RAZR series running on old Android 2.3.3 or something like that. It really works, but Motorola has removed the documentation and source code from its site.
HTC ONE X + and newer HTC phones will support the new API soon with special HTC libraries according to HTC. (At least they seem to be doing something)
The Samsung Galaxy S3 has some “secret” API that some people can use to discover devices, scan services and features (there is an app on the Google Play “Junior Bluetooth Smart Scanner” that can do these things on the Galaxy S3).
Google asked Broadcom to make a replacement for Bluez in Android 4.2. Unfortunately, this release had a lot of functionality and peripheral compatibility. Maybe because one or more Wifi / GPS / Bluetooth Classic / Bluetooth Low Energy share the same HW resources, but the drivers do not cope very well with this. Many people have problems with the latest Android Bluetooth features.
So I expected Broadcom to focus on fixing the mess, and THEN with Google will move on to adding Bluetooth 4.0. Not enough energy. Google said: "Low energy is the next BIG thing we will integrate." Not less than 1 year.
Personally, I had to buy the retina iPhone4S and iPad to get platforms that support low energy. With them, we could end the BLE peripheral sw and make the protocols work. Now we are waiting for Google and Broadcom to clean up the mess. Hopefully with some backward compatibility, so all old phones with BT4.0. clean chipsets will also open up to a beautiful world of peripheral devices matching batteries ;-) (you need to dream).
In fact, we have to wait for HTC to release its APIs, and for Google, to select / manage a standard API.
Windows Phone 8 was supposed to get BLE, but it was delayed for updating. (Lumia 920 is certified, but without an API (AGAIN !!) we are helpless developers)
There is a good GATT API for Windows 8, as well as for MAC "OS" x.
You really should invest in a TI BLE development kit, which costs $ 50- $ 100 per key, which you can use to sniff out BLE. It comes in handy to SOOO when you design your SW peripheral SW.