When Apple released its security update for Snow Leopard in conjunction with the OS X 10.7.3 update, a number of people found that itthat's required for running PowerPC applications on that version of OS X.
After updating, instead of loading and running properly, applications would crash, not be able to save new files, and otherwise behave oddly, causing a number of people who still rely on older versions of popular applications--such as Office 2004, Photoshop CS, and Quicken 2007--to no longer be able to do their work.
Immediately following news of these problems, Apple began investigating the issue, and one user issued his own revisioner to address the problem until Apple was able to fix it.
As of now, Apple has issued a new version, 1.1, of the security update, which supposedly corrects the problems in the first version. The new update is being pushed to Apple's update servers, so if you've checked and don't see an update available, then be sure to keep checking Software Update (in the Apple menu) until it shows up. So far the update has not been posted on Apple's support downloads page, but we expect it to soon be available there as well.
The update can be applied over the existing security update but is a replacement for the original security update, so if you haven't already installed it, then you can do so with this latest version and avoid the Rosetta bugs altogether.