Adsense Publishers can now track the success rate of product referrals on specific pages or websites as the channel feature is now available for referrals like Picasa, Firefox, Adsense and Adwords.
You are allowed to create upto 200 active channel names for Referrals. To add a channel to existing Adsense Referral code, either overwrite the code with the new version or just append the following line:
google_ad_channel = "Channel_Number";
My success rate with Google Product Referrals has been satisfactory. Visitors to this site are curious to know about Picasa but they just read about it on Google Website and don't download or install the software. Probably the software size turns them away. On the other hand, Firefox continues to perform well.