Here's the short answer:

A group of people that get together who happen to all have a interest in all things medieval.  Most of us have a history in the old dice rpgs such as AD&D, Vampire, Magic:The Gathering, etc...  We like to get together and pretend we're somebody we're not and just see where our imagination takes us.  Most (but not all) have had some experience in paintball as well so we're used have having our buddies hunting us like dogs.  Last but not least, we all like to beat the snot out of our friends.

Here at the MRPL, we usually focus on the combat part of the roleplaying.  I suppose we could be called the Medieval Fencing Society for all that it matters, but with time (and members) we can get more into the actual roleplaying aspect of it all.  We like to get together and make some mock and at least resonably safe weapons (you see this Will, no more broomsticks) and attempt to re-create medieval sword play at its finest.  If you sound interested be sure to drop a line, and we'll see what we can do.