This tool makes the necessary changes to enable OS X 10.10 Continuity on compatible hardware. Continuity features activated by this tool include Application Handoff, Instant Hotspot, and Airdrop iOSOSX.
● Activate continuity: Does a Continuity compatibility check, backups the original Systems kexts, disables a Mac-model blacklist in the Buetooth kext, whitelists the Mac board-id in the Wi-Fi kext.
● System diagnostic: Produces a report of the current system parameters influencing Continuity.
Here's a look at the Macs that require this tool and whether or not they require a hardware update.
There are also some Macs that don't need the tool but do need a hardware upgrade. More information can be found in UncleSchnitty's guide on MacRumors. The tool is not compatible with BT4 USB Dongles, it only works with the right internal Apple wireless hardware.
Read More [via MacRumors]