Tamagawa numbers in the function field case

The Tamagawa number of a semi-simple simply connected group over a function field is equal to 1, and the space of connections on a principal bundle is contractible.  In the 1980s, Professor Harder pointed out to me the intriguing but mysterious relationship between these two statements.  A recent proof of Weil's Tamagawa number conjecture in the function field case by Gaitsgory and Lurie using derived geometry sheds new light on this old conundrum.  I will report on this and related work.