  Results of three searches are presented for the production of supersymmetric
particles decaying into final states with missing transverse momentum and
exactly two isolated leptons, e or mu. The analysis uses a data sample
collected during the first half of 2011 that corresponds to a total integrated
luminosity of 1 fb^-1 of sqrt{s} = 7 TeV proton-proton collisions recorded with
the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign
dilepton events are separately studied, with no deviations from the Standard
Model expectation observed. Additionally, in opposite- sign events, a search is
made for an excess of same-flavour over different-flavour lepton pairs.
Effective production cross sections in excess of 9.9 fb for opposite-sign
events containing supersymmetric particles with missing transverse momentum
greater than 250 GeV are excluded at 95% CL. For same-sign events containing
supersymmetric particles with missing transverse momentum greater than 100 GeV,
effective production cross sections in excess of 14.8 fb are excluded at 95%
CL. The latter limit is interpreted in a simplified weak gaugino production
model excluding chargino masses up to 200 GeV.
