This thread is a bit old, but I didn't find "the other one" where there was some additional discussion of scanning from books.
A recent search for some stuff on current scanner models turned up evidence that there really is an apparently decent "book scanner" now on the market that might be of interest to anyone faced with doing a significant amount of such scanning, although it's rather expensive compared to simpler flatbeds.
Take a look at the review of the Plustek OpticBook 4800 if it might be something you'd need fairly often.
Additionally, I should revise my "review" of the HP8500 that I mentioned at 24 Nov 09 - 12:26 AM. The "scanner part" failed completely (within warranty) and was replaced by HP, but very soon after that the scanner functions "went dead" (no longer under warranty, of course). About three months later it resumed the ability to scan stuff, but apparently with some dead pixels in the scan bar that make incredibly ugly lines, top to bottom, on all scans.
It also had developed a tendency to jam when running the originals through the automatic feeder, and every jam damages - usually destroys - the original page, since there's no way to disengage the drive rollers and picking out pieces against the force of the feed rollers is the only way to clear most jams.
It is still an excellent printer, and makes color ink-jet prints cheaper than my mono laser printer; but it's useless as a scanner.
For my document archiving, I've gone to an Epson GT-S50 with single-sided document feed that's a little faster, and also comes with software to scan direct to pdf. In the very rare case of a jam, the entire drive opens up so you just lift the original out. The ABBY OCR software that came with it seems to do a slightly better job than the Nuance kit with the HP, although I haven't really done a serious error count on either. It has some "software problems," and doesn't do a "photo quality" job of rendering colors in all cases, but it's been extremely helpful in getting rid of > 1300 gallons of paper shreds from the documents I've run through it (so far).
I'm currently considering the need for a new flatbed scanner, since the cats have broken several pieces off our existing Canon (mostly lids and paper guides, but I don't use it much much for printing).
The reviewers indicate lots of different scanners available, but for the most part don't mention much of anything about color accuracy, scan rates, or other factors I'd like to know about. Unfortunately, the manufacturer's specs are mostly lies, so you have to "trust and assume" and place the order until you can try out what you get.