I like @DWGKNZ's answer, especially where he's saying about things tending to move forward in big bangs, rather than some gradual linear progression. You will of course find small-scale enhancements year-on-year, but these would not be big enough to convince you to get a new bike, say. I just wanted to add something about hydraulic brakes.
But also I'd say your description of a $2000 bike as "high-end" is not quite there. My definition of high-end would be more like $10-15k or so. Or, putting money to one side, I'd define "high-end" simply as the bikes the teams use.
Innovations, without doubt, will appear on higher-end bikes first. You'll have already read that the last big bang, electronic shifting, appeared in the Tour de France in 2009. But you still won't find electronic shifting on most road bikes. This is simply because it hasn't been made cheap enough yet. So if you really are looking at a $2k bike, you're still waiting for this development to trickle down.
Nobody has mentioned brakes yet, but hydraulic brakes will be the next big bang for road bikes. A very few road bikes have this right now, but once the UCI approve them for competition use (apparently pretty imminent), the floodgates will open. And hydraulic brakes will trickle down more quickly that electronic shifting, simply because the technical issues with hydraulics have already been cracked in the mtb world.
Now, you can judge for yourself how much of a technical advancement electronic shifting or hydraulic brakes will be to you. But certainly the marketing people need to use things like this to try to convince us all that the bike we bought two or three years ago is actually no good, and we need to shell out once again. There is a lot of this hype goes on in the cycling world - at the most cynical it's change for change's sake - and I think recognising the things worth shelling out for becomes a judgement call.