Many have referred to Greg Linden's prediction of a dot com crash this year. I agree that something is coming – the amount of money being thrown around is simply not sustainable. The TechCrunch deadpool will be getting bigger and bigger this year. But I suspect there won't be too many layoffs at Google, although if you've been following the Goggle share price over the last few months you'll know it is not particularly stable.
Greg's point about privacy is probably the most important, as we are seeing those effects already (a la the amusing Facebook Beacon fiasco recently).