My understanding is that tomatoes are wind-pollinated.

Well, not exactly, this is a somewhat complicated story. See for
example: http://en.wikipedia.org/wiki/Tomato#Pollination

The short version is that outdoors, it is unlikely to be a problem,
but if growing tomatoes indoors, you may need to shake them (or do
something else, as described in that article), to get them to
pollinate themselves.