Jennifer has written an excellent EFF guide called Protecting Yourself From Suspicionless Searches While Traveling:

Practically, the government has not disclosed CBP’s laptop search practices, despite our Freedom of Information Act lawsuit for these documents. We don’t know what a border patrol agent will do when confronted with an encrypted machine. One possibility is that the agent will simply give up and let the traveler pass with her belongings. Other possibilities are that the agent will turn the traveler and her machine away at the border, or that he will seize the laptop and allow the traveler to continue on. I suspect that on most occasions, CBP agents confronted with encrypted or password-protected data tell the owner to enter the password or get turned away, and the owner, eager to continue her voyage or to return home, simply complies.

You might not realize it at first, but this is in reference to the US border. I like the multiple accounts idea, especially as you can disable an account or even block it from appearing in the login window. Very stealth. One option I did not see is simply to use your laptop as a terminal and store nothing locally. If you absolutely must store files locally, then encrypted USB devices that look like pens, shoes, etc. are an option. Can’t wait to see if the new Get Smart movie tackles this issue.