ResolutionPhotoshop gurus David Blatner and Conrad Chavez are the authors of the book Adobe Photoshop CS/CS2 Breakthroughs.
Publisher Peachpit provides the visitors of their web site with a sample chapter of this book that deals with resolution.

It answers some of the most common questions people might have about resolution in the following subjects:

- Don’t Forget Your Resolutions
- Finding Out the File Resolution of an Image
- What’s the Effective Resolution?
- To Resample or Not to Resample. . .
- Going Bicubic
- Image Size vs. Canvas Size
- Resizing a Batch of Variously Sized Images

You can find the article here.