I made fun of Apple for releasing a version of Aperture that was a blatant "me too" response to Lightroom's most-admired features. So in fairness I now must point out that Aperture, while still lacking some key image editing features that make Lightroom my choice, has leaped ahead in two key areas:
Available today as a free software update, Aperture 2.1 includes the Apple-developed plug-in, Dodge & Burn, which adds brush-based tools for dodge (lighten), burn (darken), contrast, saturation, sharpen and blur. Over the coming months, third party software developers will deliver image editing plug-ins for localized editing, filters and effects, noise analysis and reduction, fisheye lens correction and more.
Lightroom, your turn for a "me too!"
EDIT: Right on cue! See comment below from a mysterious "John" who may just be John Nack of Adobe.