Hybrids are cool. They offer a higher Isp value than most solids with the potential for throttleability and inflight shutdown, with much higher safety. They're much cheaper than most liquid-fueled systems because hybrids are so much simplier. That's why Rutan choose hybrid engines for SpaceShipOne.
Of course, hybrids have disadvantages compared to liquids, such as the weight penalty of the casing and lower Isp. However, for some applications, hybrids are a good solution. I wonder if a composite wound casing would help offset some of the weight penalty. Beale was working along those lines with his project several years ago, but his casing wasn't exposed to the heat of combustion, just the pressure (he didn't use turbopumps but instead used compressed propellant tanks).
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re: Hybrid rockets