There's certainly a tradeoff between shotgunning and carefully crafting an individualized approach. I'm not sure it's really all that different from what it's always been though. Way back in the day when I was graduating from engineering school, I sent out a lot of minimally customized cover letters with a standard resume to many companies in what seemed like possibly interesting industries. In fact, I got a number of interviews from those shotgunned resumes and ended up working at one of the companies. It was a pretty good job and one that I'd have never stumbled onto with a more tailored approach.

OTOH, my most recent three jobs--including my current one--were all basically through people that I knew.