Over the last year or so Lightroom has really accelerated forward as far as built in noise reduction techniques, as an Aperture user myself I think we can use whatever we can get from third parties. Noiseware today has announced that version 5 of their software is now compatible with Aperture 3. This version supports multiple cores (64-bit), ability to save presets and unlimited undos with all of the history from your current edit.
The plug-in is available now and you can also get a free trial here that allows you to test drive it for 15 days. The full price is $79 but will allow you to update for free to all incremental updates (5.1, 5.2 etc.). There is also a 32 page PDF that goes into overview of all of the features and shortcuts here.