The most appealing possibility – a weak scale dark matter particle interacting, like neutrinos, via Z-boson exchange - leads to the cross section of order 10^-37 cm^2 which has been excluded in the 80s. There exists another natural possibility for WIMP dark matter: a particle interacting via Higgs boson exchange. This would lead to the cross section in the ballpark of 10^-43cm^2 (however strongly depending on the Higgs mass, and also on the coupling of dark matter to the Higgs) which is currently being probed by experiment.
If Xenon100 see nothing, it is a good moment to seriously start worrying whether the WIMP paradigm corresponds to reality, although models that predict even lower cross sections do exist. In the worst case dark matter may be very weakly interacting (axions, gravitinos) or very light (keV-MeV scale dark matter), in which case the direct detection searches are doomed from the start.
For the next decade or so the direct detection will go in the direction of monster detectors that will allow us to improve the sensitivity down to 10^-47 cm^2. Preparations for a 1 ton xenon detector are already well underway, while 10 ton xenon detectors are on the drawing board. Actually, it’s not the size of the experiment that is the limit here. When the sensitivity reaches 10^-48cm^2, probably sometime in the next decade, these searches will encounter the background of atmospheric neutrinos and diffuse supernova neutrinos. Thus, asymptotically, dark matter detection will merge into neutrino physics[.]
Current boundaries suggest islands of possibility around 10 GeV mass and 80 GeV mass. There are no rumors of ground breaking new discoveries, but are rumors that results from Xenon 100 may be delayed due to difficulties in data analysis.