#1. "RE: What is Adobe Lightroom?" In response to Reply # 0
One of the best ways to learn about LR is to take a "tour" on the Adobe LightRoom web site.
LR is stand-alone program that is used to ingest, catalog, label, edit, print, upload-to-web, manage sites like SnapPix, construct slide-shows, etc. It's editing tools are very intuitive and do most of my RAW editing. For more difficult layers stuff, I open CS5 from within LR and do the work there. LR allows you to import say 100 images and work with them in blocks applying lighting and other corrections to images ranges within the 100 (assuming you shot these images in different conditions). This is very, very useful. IMO worth the cost of the program alone.
I can import a block of images, assign basic keywords, make basic lighting and other edit corrections, rate them, cull, etc in a matter of minutes with a consistent set of libraries, catalogs and editing tools across a multitude of images. The discipline itself speeds long term collections and displays of images.
LR offers a generous 30 day trial. It's worth it because you get a fully functioning piece of software. It wouldn't recommend trying the trial until your schedule permits time to devote to the software for those 30 days. It's a shame to miss major features because you didn't allow enough time.
#3. "RE: What is Adobe Lightroom?" In response to Reply # 2
Sorry, I haven't used NX2. I understand that it is a powerful single-image editor (my characterization) that is capable of applying the Nikon in-cameras settings to the RAW images as they are imported and converted from RAW to jpg/tif. LR can't read all the Nikon proprietary settings so you basically start with the RAW image and apply yours or other preset editing steps in the conversion process.
LR saves all it's images modification in a database or sidecar files so the original image is not effected by any editing steps. Once you export an image (copy) from LR to an external file/format, the editing steps are permanently integrated into the exported file.
I hope someone else with more info can help you. I think LR has conditioned me to not think about Nikon in-camera camera controls. It RAW converter is very powerful and so are standard or your customized presets, but it does ignore the Nikon in-camera settings.