If you haven't noticed lately, there is a major "horse race" going on between Lightroom and Aperture. Many beginning real estate photographers are trying to decide which application to buy. Ian Wood wrote a detailed comparison of Lightroom/Aperture Pros and Cons over at O'Reilly DigitalMedia blog that is well worth a read if you are trying to decide which way to go.
Creaceed released a beta version of Hydra 1.5, which I think is the first instance of a HDR application that is a Aperture plugin. For more details on Hydra see the review by Pat St Clair at VRMAG. I like the idea of being able involve these kinds of image processing applications from withing your workflow software.
PTLens by Tom Niemann now runs on Intel Mac computers under Mac OS 10.5.2 (Leopard) or later with a monitor resolution of at least 1280x800. This is a great little application for fixing barrel distortion. See the in depth explanation of how PTLens works by Uwe Steinmueller over at Digital Outback Photo.