Today, search engines does'nt have problems with URL's including the question mark and the cryptic string after it. Google searches and stores since a long time the pages and URL's.
But people dont want to have that, people dont want to write a URL like "zappr.de/default.aspx?id=images&user=somewhere", people want to write "zappr.de/images/somewhere/default.aspx". And now, we have FPO URL's. A FPO is a "for-people-optimized" URL.