AirDrop is a new feature in OS X Lion that lets you wirelessly send files to other OS X Lion users, without Wi-Fi. But it only works on certain Macs. Apple has posted a KnowledgeBase article explaining which ones work:
Macs that support AirDrop in OS X LionThe following list shows the earliest of each Mac model type that is supported. If your Mac is the same, or newer than the model listed, then it supports AirDrop.
- MacBookPro (Late 2008 or newer)
- MacBook Air (Late 2010 or newer)
- MacBook (Late 2008 or newer)
- iMac (Early 2009 or newer)
- Mac Mini (Mid 2010 or newer)
- Mac Pro (Early 2009 with AirPort Extreme card, or Mid 2010)