Behold the power of Wikizon: Amazon adds ProductWiki

While you were blinking, Amazon.com added ProductWiki

A list of Wikis you have contributed to appears on your Your Amazon Home and Profile pages.

What Should You Put In A Wiki?

Think of a Wiki as an encyclopedia entry that everyone who comes to the page will read. You should put in relevant factual information that you believe will be of value to others who visit the page. A Wiki is not the place to express your opinion; that's what Customer Reviews and Customer Discussions are for. As always, please treat the Amazon community with respect by not writing inappropriate or off-topic comments.

from http://www.amazon.com/gp/wiki/what-is-this.html

The editing controls are basic: bold, italic, remove formatting, and Wiki link.  I'm not completely sure what "Wiki link" does.

ProductWiki does not show up on all items, and like many "Amazon has added..." features, it doesn't show up on Amazon.ca

I found it on e.g. Son of a Witch: A Novel, on my screen it's right after "Customers who viewed this book also viewed" but who knows what Amazon's customization mindreading does to the page format you may see.

Amazon is also experimenting with Customer Discussions (basically discussion fora, post a message, post a reply kinda thing) and with tagging.

Info via Slashdot Amazon Goes Wiki /.
Wikizon terminology from BusinessWeek Tech Beat blog.

Meanwhile, your OPAC... oh your sad little OPAC, all quiet in the corner.
Don't feel bad.  Remember, your OPAC should never be your user interface anyway.