While Hurricane Irene failed to produce the 100+ mph wind catastrophe many predicted for New York City, massive flooding in Vermont is going to make Irene the 10th extreme weather disaster of 2011 with damages to exceed $1 billion - breaking a record just set in 2008.
How climate change will affect hurricane frequency and intensity is a highly complex question with lots of variables, but the case for climate change causing more intense atlantic hurricanes is currently ambiguous at best. Hurricanes will almost certainly be wetter (due to higher sea surface temperatures and atmospheric moisture content), but increased wind shear will probably make it tougher for them to form and also make their cyclonic winds weaken rapidly upon landfall (which is what we saw with Irene). With increased precipitation and higher sea levels historic flooding will occur, but probably not historically unprecedented wind damage…from hurricanes.
However, winter storms and thunderstorms will massively intensify, as wind shear (when winds at different levels in the atmosphere blow in different directions) actually drives these storms along frontal boundaries. Paradoxically, violent blizzards will probably be one of the most impactful weather phenomena (at least in North America) signalling global warming.