I have been to a few "backwater" strips where UL pilots do not use radios but here in Illinois it is rare (for me anyway in 2012) to find a "UL" pilot who does not have a radio. In my circle of about 15 aircraft (about half have N-numbers) there are only a couple that are radioless and they mostly don't go anywhere. One of them is a GA pilot who thinks he doesn't need one since it's an ultralight). Besides having a way to talk to friends, the radio, and proper pattern usage do more to gain acceptance at uncontrolled airports than anything else. I started flying a UL trike into GA airports 14 years ago. In some case they had never even seen a trike before, but the radio and pattern flying made me welcome.