First off, nice article. I especially appreciate your list of "manageable content items."
For about 2 1/2 years I've been making sites based on the idea of using web services to stitch together disparate content around topical interest areas.
More recently however, the number of available services has started to balloon, and I've been able to (relatively) quickly create two mashup sites for timely topics.
The first site pertains to the Supreme Court and garnered traffic based on interest in the John Roberts nomination / confirmation hearings.
The second site, just launched in stealth mode yesterday, centers around the forthcoming launch of the Xbox360. NOTE: Much work still to be done on this one and apologies in advance to the Mac Safari folk for some layout inconsistencies.
These sites stitch together so many technologies I need a thimble to work on them!
+ Blogs from Technorati
+ Bookmarks from del.icio.us
+ News stories from Google News
+ Products from Amazon
+ Backpack / Backpack API from 37signals as a web-based CMS
Examples at http://tinyurl.com/cb3ft and http://tinyurl.com/acwgg
+ Feedburner for feed clickthrough tracking
However, there's one part of the Web 2.0 story that none of the pundits seem to be talking about... legal issues.
Basically, the license agreements from most of the players large and small prevent commercial development. Even my sites are questionable, though truth be told I have yet to make a dime in Amazon referrals and have spent plenty of time and money on my code-base over the past few years. (As my mom says, sounds like a "great" business plan!)
I have to imagine these restrictions will have a chilling effect on development of high-end mashup sites and other types of Web 2.0 projects.
Importantly, some of these agreements, such as Amazon's, prevent you from commingling services in certain ways. For example, you can't place links to eBay auctions alongside product details provided by Amazon.
See the section "C. Linking and Diversion" of their agreement (http://tinyurl.com/8x42c) for specific restrictions and other legalese.
So, while you could provide both services within a single site, actually "mashing" them together in a singular context (i.e. the part with the most exciting possibilities) would be prohibited.
Either way, I'm excited about all of the new and novel sites that are springing up and making use of the various technologies under the Web 2.0 umbrella.
oreilly [at] toddlevy [dot] com