I never answer questions about my past or expected salary, not to employers and not to recruiters. Most employers don't ask, and the few that have (perhaps by having a part of an employment form ask for previous salary) have never made my leaving that information out an issue. Most recruiters, if they even ask, respect my decision not to talk about it, but I've been pressed hard on this by a handful of recruiters, an…
EDIT: Also I kind of disagree with your assessment that it's a "seller's market" for IT talent. A lot of companies appear to be fishing for good deals, but is there really that much actual hiring going on? A lot of companies saying they're looking for talent does not a hot job market make.