A security update to WordPress, has been released in the form of WordPress 2.9.2. You should update your WordPress site right away.
From the WordPress Blog:
Thomas Mackenzie alerted us to a problem where logged in users can peek at trashed posts belonging to other authors. If you have untrusted users signed up on your blog and sensitive posts in the trash, you should upgrade to 2.9.2. As always, you can visit the Tools->Upgrade menu to upgrade.
If you require assistance upgrading, please contact us anytime.