I've a working version of a Raspberry Pi with a Bluetooth 4.0 (CSR) dongle that detects iBeacons (estimote) proximity using latest BlueZ.
It's working great but I don't know if I need a BT 4.0 capable device, or I can detect iBeacons with an older BT 2.0 dongle.
Does anybody have the answer or a pointer where I can get more info?
Yes, you need a Bluetooth 4.0 dongle to detect iBeacons, because they are based on Bluetooth Low Energy, aka Bluetooth LE, which wasn't released until the 4.0 Bluetooth spec.