Lightroom 4 Review
The other new module in Lightroom 4 is the Book module. Rather than taking the approach Apple has with it's own publishing service, Lightroom 4 integrates with Blurb for publishing. There is an Auto Layout feature that will flow your images only pages, and you have full control over the layout of individual pages. There is a 240 page limit to books. If you don't want to send your book off, you can also output as JPEG or PDF.
One of the biggest, and most welcome changes, at least for many pros that do their own printing, is the addition of Soft Proofing to Lightroom 4. Perhaps the most frequent complaint in earlier versions, Lightroom now supports soft proofing is a very logical way. Although it's found in the Develop module, I've placed it here under Printing because that's what most people associate soft proofing with. By enabling this option (View > Soft Proofing), the histogram area changes to reflect the paper and rendering intent chosen. Changes made to your image based on this proof are saved as a Proof Copy - essentially creating a new Version automatically to protect your adjustments for other output options.
Within the Print module, there is now the option to adjust the printed output for brightness and contrast if needed. These adjustments apply only to the printed image and that particular profile. Although my experience is that if your monitor is properly calibrated and you're using the correct printer settings, you shouldn't need to make an adjustment here, the option is available if needed.