Laptop search at US Customs. Does Encryption help?

According to an article on CNN.com (see article) US Customs- and Border Protection agents are legally allowed to search your laptop. They don’t need a valid reason to do that, everybody is subject to this search. While I certainly don’t have anything on my laptop that would put national security into any sort of danger, it still feels strange thinking that this person I have never before seen in my life suddenly might go through my personal files.

I assume that if they find an encrypted area on your hard drive, they have their methods of “convincing” you to open it (as long as they can find it) At the same time, what if someone REALLY needs to hide something? Couldn’t he just encrypt it, send/upload it to a server or email account, delete it off his hard drive, and then simply download it again after having entered the US? If someone is smart enough to do that, then they can search his laptop as much as they want, they will still not be able to find anything.

So what exactly are they trying to achieve with this law? Finding another way to delay waiting time on border and customs control?