You could always buy xMarkPro (see sig). Next upgrade coming out tomorrow will also contain an automated backup & revert feature for domains (including WP blogs). For example, have your blogs backed up every 3 hours. If someone hacks it, it's the click of a mouse, and it's back online. Plus have your blogs automatically updated when WP releases new versions, ensuring you're always running the most stable version.
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xMarkPro -- Ultimate Blog Network Management
Streamline your marketing operations. Centralize management of domains, pages, Wordpress blogs, sponsors, link codes, media items, sales and traffic statistics, plus more!