>So how many patents have you seen overturned, vs. how many have been upheld?
>Just curious...

Check out the reports at www.fedcir.com (its more easily readable 
from the Emory cite you can click to from there).  You'll see that 
the cases that go up on appeal tend to split fairly evenly on 
validity.  A case overturning or sustaining validity seems about as 
likely to be reversed as affirmed.

This is not to say that half of the patents asserted are declared 
invalid.  Most cases do not go to appeal.  (The Federal Circuit is a 
bit trigger-happy in sanctioning frivolous appeals--a good thing, 
IMHO).  For the ones focused on validity as a sole defense, FedCir 
may be the first meaningful line of defense.