Beilinson obtained a formula relating the special value of the L-function of
H^2 of a product of modular curves to the regulator of an element of a motivic
cohomology group - thus providing evidence for his general conjectures on
special values of L-functions. In this paper we prove a similar formula for the
L-function of the product of two Drinfeld modular curves providing evidence for
an analogous conjecture in the case of function fields.