It's an easy generalization to make, but often times, it is said without any discernible proof as to one way or another. Personally though, I believe the rich have also gotten poorer.
For example, let's take a look at
wikipedia's list of billionaires. I realize that wiki as a source should be taken with a grain of salt, but if there any truth to the listing, you'll see that most of the billionaires have lost much of their capital in 2008. And that makes sense. After all, most own companies or at least stock, and the stock market tanked in 2008.
Of course, it is indeed possible for the rich to get richer. They have more capital, better networks, more options.... But the reality is, the rich doesn't always get richer.