Since poor Facebook doesn’t have a simple way to do that, it’s now possible with Greasemonkey script called Facebook Purity.

It removes all messages posted by applications to your homepage and gets rid of messages about quizes etc, basically all messages from any applications created by external developers. Just leaving messages from the original facebook apps such as status updates, wall posts, links, notes, photos, etc behind.

The latest version of the script lets you see how many app messages have been blocked, and to show or hide them again. It puts a little message in the top right hand corner of your page.

Links:
Greasemonkey add-on for Firefox
Facebook Purity script
How to remove attending, fan, group and “now friends” messages from Facebook