After nearly a year of unstable, flaky releases KisMAC has a stable version 0.21a. This new version is not only stable but comes with some new features as well.

• passive AirPort Extreme mode (except for MacBookPro and newest Mac Minis)
• KisMAC is now a Universal binary
• IP-Addressen of Clients will be shown
• Extenended configuration capabilities
• Growl integration
• Google Earth export
• Advanced search options
• Reworked Atheros integration

For those who don't know what KisMAC, is it's a stumbler application that can put your card into monitor mode. It supports multiple third-party PCMCIA and PCCards and, naturally, Airport cards.