The economy is still stinking, but there is pent up demand for vacations, even if it is just road trips. With the fact that bedbugs are a menace, people are willing to pay the price for a decent RV just to have their own bed.
Then there is the fact that alternative vacations are becoming less of an option. Cruises have had bad press, airplane travel is a nightmare, and Disney World hiked their rates so a ticket is about a C-note/day. So, having a decent RV and being able to take trips is something that is coming back.
Here in Central Texas, CGs are packed. To boot, new RV parks are springing up to handle the demand.
How long will it last? Likely a while -- gas isn't getting any cheaper which gets people to roam close to where they live.