  We summarize our recent results on the resummation of hard-scattering
coefficient functions and on-shell form factors in massless perturbative QCD.
The threshold resummation has been extended to the fourth logarithmic order for
deep-inelastic scattering, Drell-Yan lepton pair production and Higgs
production via gluon-gluon fusion. The leading six infrared pole terms have
been derived to all orders in the strong coupling constant for the
photon-quark-quark and the (heavy-top) Higgs-gluon-gluon form factors. These
results have many implications, most notably they lead to a new best estimate
for the Higgs production cross section at the LHC.
