Apple released an update to Aperture 2, version 2.1. Rob Galbraith reviews it here. One of the most exciting on one hand and most disappointing on the other is the inclusion of a plugin architecture. This architecture allows third-party developers (which includes all of us if you register as a developer at Apple BTW) to create plugins that can be used right inside of Aperture. Many photoshop plugin developers, such as Nik and PictureCode have jumped on the bandwagon. The surprising thing to me about these plugins is that they are more like photoshop plugins than like RAW development tools. They do not sit in the RAW pipeline, but are called by rendering a tiff file and sending that off to the plugin. This means that all of your Aperture adjustments are "burned in" when you call the plugin. This is a pity as it breaks the RAW paradigm of the program and really is nothing more than a fancy way of using an external editor. This of course makes it extremely easy for a third-party developer to program for as they can simply reuse their already existing Photoshop plugin code, but does not push the envelope at all and severely limits the usefulness of the plugins in my opinion. I really hope that Apple is also developing a second plugin architecture that allows for non-destructive RAW plugin tools that work in the same way as the color balance sliders for example or the clone/heal tools (for dodging burning).
P.S. what is very interesting is that Apple apparently allows plugins to access the actual RAW data. This means that you could use alternate RAW interpreters directly in Aperture, potentially circumventing some of the issues Apple's RAW engine still has.