I've tended to stay away lately from the arguments about scientists-as-communicators that seem to flare up periodically. This recent editorial by Chris Mooney, about how scientists who actively listen to the general public do a better job of communicating and affecting policy, was simultaneously informative and yet blindingly obvious in some ways. (Here's a shock: making it clear to an audience that you're listening to their concerns and considering them seriously gets better results than talking down to them or ignoring them dismissively.) Chad Orzel followed up with a very well-written (as usual) post about scientists and communication skills that is, like Mooney's, really common sense in the end. (Here's another shock: not everyone is Carl Sagan or Neil DeGrasse Tyson, and sometimes our scientific and academic institutions do not value public communication as much as they do utter dedication to scientific research.)
Many people in the general public do have some baseline interest in science and engineering issues, even if they don't label them as such. Lots of people watch Mythbusters. Lots of people read about nutritional information or medical research quasiobsessively. Many people do care about space, and climate, and the environment, and energy, and electronics, and so forth, even if those concerns are not the top of their list all the time. There is a thirst for information, and this is all good for society. I do want to point out one additional issue that seems to get neglected to some degree in this discussion, however. There are people out there who either don't know what they're talking about (the MD who somehow has a column on the Huffington Post who periodically spouts off utter pseudoscientific nonsense), or actively are pushing misleading or inaccurate information (members of the TX Board of Education who grossly mischaracterize the nature of science). Scientists can do as much as possible to "market" ourselves and communicate our enthusiasm and willingness to have an honest and open dialog about scientific issues. However, when anti- or pseudo-science can command at least as big a bully pulpit, and when education and time make it difficult for the average person to discriminate between gold and dross, it's an up hill struggle. Add in to this the mainstream media's love of controversy ("Some say that the earth goes around the sun, but others disagree. Let's look at both sides of this issue!"), and the situation can get downright depressing.
Edit: I realize I left out two other confounding factors: (1) Scientists who end up distorting actual science beyond recognition in a misguided attempt at popularization (Michio Kaku is an example); and (2) Scientists who are so aggressively arrogant and obnoxious that they only hurt their own cause.