Improved Highlight and Shadow Recovery. Bring out all the important detail that your camera can capture. New technology brings in more image detail from dark shadows and bright highlights than ever before.
Location Based Organization. Adobe added a brand new map module that allows you to organize your files by location.
White Balance Brush. A flexible brush lets you refine and adjust white balance in targeted areas of your shot.
Soft Proofing. Soft-proofing lets you preview how an image will look when printed with color-managed printers.
Superior noise reduction. Achieve amazing, natural-looking results from your high ISO images with state-of-the-art noise reduction technology. Apply noise reduction to the entire image or target specific areas.
Extended video support. Organize, view, and make adjustments to video clips.
Additional editing brushes. Expand your creative control by targeting particular areas of your images using new local editing brushes for noise reduction and moiré removal.
Photo book creation. Create beautiful photo books from your images with a variety of easy-to-use templates included in Lightroom 4.
Enhanced online sharing integration. Easily post images to social media and photo sharing sites like Facebook and Flickr®.
Import of other libraries. Bring the power and elegance of Lightroom to all your images, new and old. Easily import photos from other applications.
If you need some guidance with Lightroom 4, you can pick up a copy of Adobe Photoshop Lightroom 4 for Digital Photographers by Scott Kelby, The Adobe Photoshop Lightroom 4 Book: The Complete Guide for Photographers by Martin Evening or Adobe Photoshop Lightroom 4: Learn by Video by Mikkel Aalan. Any of these titles will make a great reference on Lightroom 4.