I found this really good article on the subject right here. It's by Andrew Rodney - Photoshop guru and NAPP Hall of Fame inductee - over at The Digital Dog.net.
Want more, check out this Highlight/Shadow recovery technique over at DigitalGrin right here. The author even used the fabled LAB mode to make final tweaks to the image. OK, one more for the road. You walk out of the shadows of your life into some better illuminated detail - then check out this last and final article on shadow recovery right here.
OK, it wasn't the last - OutbackPhoto had a contest on Highlight/Shadow recovery right here. Check it out - you get 8 solutions for the challenge. I've posted the BEFORE here and followed up with my favorite AFTER - give a peek below.