Surprises me that so many are just discovering Wordpress..
To those wondering how you can update 500 WP sites are assuming that all of them are traditional blogs...Nothing says you have to use WP for a blog. WP is a great platform for simple 3-4 page sites with static content that doesn't require regular updates.
All the plugins available allow you to build sites that update themselves or/and allow user generated content so many updates happen on their own.
Classified Ads, Forums, Social Network features, Review sites, Tubes, TGP's ecommerce...the list is endless with more being added all the time.
IMO WP is the most versatile, well supported, user friendly platform that exists to date.
I use WP for all my parked domains, build mini sites on them, add some well written SEO text, highly targeted ads and bam yer done and listed in the SE's within days... They have been beating traditional parking service revenue by as much as 8 times on some of my parked domains and gotta love the SE benefits and the control over the pages, plus its not bad for a little link love on occasion either.
a cpl handy wp related links:
I want a WordPress Plugin to ... 450+ solutions.
Wordpress Plugins to solve your common blogging problems:
http://www.econsultant.com/i-want-wo...ins/index.html
Non traditional uses for WP:
http://designm.ag/design/11-non-trad...-of-wordpress/