Today Apple released Aperture 1.5, a huge upgrade that’s available for free to current Aperture owners via Apples Software Update.

Here’s some text from Apple’s website:
Aperture 1.5 delivers compelling new features, including flexible library management that lets you store images anywhere you’d like. The free update also introduces third-party extensions that let you use Aperture as the front end to an expanded workflows. Aperture 1.5 offers RAW support for more than 50 camera models from a wide variety of manufacturers (including Canon, Nikon, Fujifilm, Sony, and others) and extends support to all Intel-based Macs — from the Mac mini and MacBook to the Mac Pro.

For more info check out Apple’s site