"Anything longer, especially if there is a lot of long-term stasis on a resume (e.g. "tech lead on product X" for more than a year or two), is an indication to me of someone who either isn't capable of stretching himself or doesn't want to. "

Or someone who's found a technologically complex niche they like and feel they can grow in. For example, two years is a really _short_ time to achieve anything in my niche (CAD, more or less).