Not sure if this is a Snow Leopard thing or not, but apparently when you hold down the option key and click on some of Apple’s menubar icons you get additional information from the application.
Here’s some examples:
Volume Icon:
By holding down the option key you now have the ability to select your input and output sources. Previously I had used sound source to do this.
Airport Icon:
Holding down the option key and clicking the icon now gives you details about your routers settings.
Battery Icon:
You can now get status warnings for your battery. Pretty cool. Conditions that might pop up are Normal, Replace Soon, Replace Now, and Service Battery. It’s nice to know that your computer will let you know before the battery explodes.