google adsense news On Referal units

If you're currently displaying referral units on your site

directing users to sign up for AdSense, read on below for details
about what to expect in the coming weeks.

In early January, the option to add referral units directing users
to the AdSense product will no longer appear in your account. You
will continue to accrue earnings for all existing referrals yet to
generate $100 until late January, at which point the program will
be fully retired. Existing referral units will continue to appear
on your pages.

By the end of January, you should remove all referral units
directing users to AdSense from your pages. Referral units
that you do not remove will continue to be displayed on your pages
as normal, but conversions will no longer be recorded. We
suggest you replace the AdSense referrals with referrals to
another product or service or an additional ad unit.