Today Apple announced Aperture 1.5, with some significant enhacements.
Stolen shamelessly from the What's New page:
1. Flexible Library Management
With Aperture 1.5, you decide how and where to store your images.
Import them into a managed Aperture library and let Aperture take care of keeping track of your images. This option lets you keep all your images in one location and offers a simple backup mechanism via the Vault.
New Open Library
Or store your photographs wherever you’d like — on any number of hard drives, network volumes, CDs, or DVDs, and have Aperture “reference†them. No need to copy the entire collection into a single managed library, simply point to them and let Aperture catalog them in place. You can even reference the images in your iPhoto library, using them in Aperture without having to move or copy them anywhere.
However you store your images, Aperture 1.5 keeps track of all the metadata you add and versions you create. And because your RAW originals don’t have to be online for you to browse or search through them, you can take your entire library with you wherever you go. On your MacBook, for example.
There is a three pass edge sharpening tool (good, as the previous sharpening controls were a little less flexible than I would desire), Hue/Lightness/Saturation controls with greater finesse (ie control of H/S/L on specific colours only, as per Photoshop), and a variety of other goodness.
Best of all, as a point upgrade rather than a full version upgrade, existing users will be able to update for free via download later this week.
<edited for a typo>