It usually runs about $200 (on amazon), $300 directly from Adobe. They have a 30 day free trial from Adobe's site. Info on it (and a link to the trial download button) is
HERE
It's basically, as I had it described to me, Photoshop re-imagined for actual photographers. You can't really do image "editing" or creation like Photoshop lets you do, but it lets you do all the image tweaking very, very easily -- white balance adjustment, color curves, cropping, noise reduction, clarity, etc, etc.
A friend of mine who's a professional photographer (and who I continually bother with inane beginner questions, poor guy!) pointed me at Lightroom, and I love it.