If you are going to celebrate 20 years of brewing, you might as well go for a 20% ABV beer because at age 30 trying to hit 30% ABV is much, much more difficult. So enter Higher Math from Dogfish Head which is coming to market in October.
It is a golden ale that is then fermented with both cherries and cocoa nibs. Probably not in large amounts so look to your favorite beer bar and see if they will have a special party to celebrate what may be rare kegs.