How best to keep multiple Wordpress sites patched and secure?

In May 2007, a study revealed that 98% of WordPress blogs being run were exploitable because they were running outdated and unsupported versions of the software

Source: http://en.wikipedia.org/wiki/WordPress

If you’re a WP developer and you’ve got lots of clients using WP, it strikes me that you’ve an onus of responsibility towards your clients and your hostng server to help ensure that (at least) security patches are applied promptly.

Bearing in mind that I’m a web company business owner/manager as opposed to a WP developer - how do you go about ensuring that security patches are applied promptly?

A little Googling suggests that Subversion is the way to go:
http://www.fullspeedseo.com/featured-articles/upgrading-multiple-wordpress-installations
http://codex.wordpress.org/Installing/Updating_WordPress_with_Subversion

Any other comments on this issue?

Thx.

Thank you for your post,I like it!

I just noticed this too:

http://codex.wordpress.org/Installing_Multiple_Blogs#WP-Create_and_WP-Mass-Upgrade

Itomic use Wordpress?

Actually, not very much to-date, but we might do more in the future. Which is why we’re conducting this basic research now so that we do it very well from day 1, rather than work all this out a year later when keeping multiple Wordpress sites security patched is becoming an absolute nightmare.

We pride ourselves on being a solutionS provider, as opposed to a solution provider. So we’re quite prepared to review a clients business needs and budget, and if we evaluate that Wordpress (or any other solution for that matter) is the best fit, then that’s what we’ll recommend.