http://img89.imageshack.us/img89/2534/appsreferralff2.png

Advertised product: Google Apps
Account used 4 consecutive weeks (description) $5.00

No words on the Inside AdSense Blog yet.

I'm only seeing:

   * Google AdSense
   * Google AdWords
   * Firefox plus Google Toolbar
   * Google Pack

I guess it's US only again.

Does it say anything about it needing to be a Google Apps Premier Edition sign up?

Nope, just "Google Apps".

"You will earn $5 when someone clicks your referral and signs up for *Google Apps* with a domain that has not already been signed up for the service. The domain must then have one or more Google Apps email accounts in use for four consecutive weeks."
http://www.google.com/support/a/users/bin/answer.py?answer=62598

Official: http://adsense.blogspot.com/2007/04/introducing-google-apps-referrals.html

I can't see in my account. The post doesn't say it's US-only, just English-only.

Here you go.
http://googlified.com.googlepages.com/app-referral-buttons.html

Cool, updated the post, thanks!

Argh..... If they'd have done that before I started pushing my customers to it, I'd probably already have at least $100 or so...

I don't see the option in my Adsense, so it must not be for everyone :(