For your information Picasa is available in multiple languages but Google Pack is only in US English. To display Pack and Picasa referral buttons on your site, all you have to do is select Referrals from the AdSense Setup page of your account, and then select the product of your choice.

It seem to me that Google are getting into affiliate marketing, with 5 referral option made available, this is good news for bloggers. What are you waiting for? Join Google Adsense now!

p.s. Usually referral products generates little to almost nothing. Depending on the content of your site. If you’re blog is about blogging, I think the Adsense buttons will be more effective. If you’re blog is about photography then the Picasa thing might net some income. Other than that, your chances of making decent money out of the referral product is minimal.

Source : Inside Adsense