  For primes p greater than 3, we propose a conjecture that relates the values
of cup products in the Galois cohomology of the maximal unramified outside p
extension of a cyclotomic field on cyclotomic p-units to the values of p-adic
L-functions of cuspidal eigenforms that satisfy mod p congruences with
Eisenstein series. Passing up the cyclotomic and Hida towers, we construct an
isomorphism of certain spaces that allows us to compare the value of a
reciprocity map on a particular norm compatible system of p-units to what is
essentially the two-variable p-adic L-function of Mazur and Kitagawa.
