  Building on the rare pion and muon decay results of the PIBETA experiment,
the PEN collaboration has undertaken a precise measurement of B_{\pi e2} =
R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul
Scherrer Institute, to reduce the present 40\times experimental precision lag
behind theory to ~ 6-7\times. Because of large helicity suppression,
R^\pi_{e/\mu} is uniquely sensitive to contributions from non-(V-A) physics,
making this decay a particularly suitable subject of study. Even at current
precision, the experimental value of B_{\pi e2} provides the most accurate test
of lepton universality available. During runs in 2008-10, PEN has accumulated
over 2\times 10^7 \pi_{e2} events; a comprehensive maximum-likelihood analysis
is currently under way. The new data will also lead to improved precision of
the earlier PIBETA results on radiative \pi and \mu decays.
