I don't see too much of that. They tend not to poach people and put them on the same accounts unless they have a special relationship. If I went to a competitor I would not want to be the Consultant for my old accounts.
I'd still meet my old accounts socially, i've become quite the city socialite, but I would not want to work with them professionally for a good few years for the obvious integrity reasons. I'd also probably not do the same role because I couldn't honestly say someone elses products are better, I know it's not true. I'd move into a different field with a different company - maybe pure services, storage security, Vmware specialism, etc.
If you dig up my old threads i've actually considered a move to New Zealand for a few years for a change of scenery.