question about engines

Ok,this is probably an obvious question to many of you, but I'll ask
anyway. I usually fly in C172s and C182s with the Lycoming oil cooled
engines that many of you are probably familiar with. I still see planes
with the large radial engines (for instance, like what you would see on
a Dehavilland Beaver) flying around. I had thought maybe these were
just old planes that were well taken care of and still flying after all
these years.....BUT... It seem like the radial engines are popular in
bush flying, and I even see a number of seaplanes with Kenmore Air
(local small airline/airtaxi) with them in use.
1) are these engines still be manufacture on any new planes?
2) Are there any significant advantages to them over the "newer"
engines?

After doing some hunting around for info, I've gotten many varied
answers, but nothing concrete. The main answers I've gotten indicate a
power advantage and the benifits of air cooling father than liquid.
Anything else any of you can think of?

Thanks for your thoughts.!