My favorite fact from last night's Coffee: Comparative Brewing Methods wasn't about brewing methods at all, but about the coffee beans themselves: Coffee is seasonal. Just like anything you pick up at the farmers market waxes and wanes over the year, coffee beans are the same way.
Let's take Guatemalan coffee as an example. It's harvested between December and March, but there's about a 3-month lag between harvesting and shipping, so you won't see it on shelves until March or so (and it doesn't run out until July).
Coffee from Java, though, has its run between August and November. Ethiopia? February through June. Kenya pokes its head out a few times during the year, thanks to a fly crop - a second harvest that happens a few months after the main harvest finishes.
Right now we're in a low period for coffee beans - most major harvests haven't started shipping yet, so we're working from stored beans. What you drink is freshly roasted, though, so it isn't quite like liquid leftovers.
Interested in knowing the best months to snap up a Colombian or a Sumatran? Check out Sweet Maria's Coffee Production Timetable. Fair word of warning: everyone on the internet has a different opinion about when each country's seasons are, but Sweet Maria's sure has the best-looking chart.