You may remember hearing about China's plans to control the weather during the 2008 Olympic Games in Beijing by attacking shady clouds with artillery and aircraft. Along similar lines, scientists in New Mexico decided to mess with thunderclouds, but with fancy lasers.
The researchers harassed two passing storms from their evil fortress (or observatory) with a high powered laser, fired in pulses. The laser light managed to generate clusters of plasma filaments that, in turn, caused electrical discharges within the thunderheads. It wasn't enough to get those coveted air-to-ground lighting strikes, though.
Why are they doing it? Being able to trigger a gen-u-wine lightning bolt would allow scientists to study their effects in a controlled manner, such as the effect of lightning on power lines and aircraft. It'd also allow them to ruin someone's day. Over and over.