easy to get around
This has been all over geek forums for a week now. The long and short of it is yes they can confiscate any data retention device (not just laptops, portable hard drives, thumb drives, MP3 players, etc). However if you were to actually get stopped, and you don't refuse to log in for them, they shouldn't be taking your laptop (unless they actually suspect you of something).
Ways around it:
1) encrypt everything - bad idea, if you don't decrypt it when they ask, they will definitely take it.
2) Scrub most of your computer clean before traveling, carry a few versions of your important stuff in different forms encrypted (say on a DVD and a thumb drive). This is less likely to raise eyebrows, however they wil still confiscate if they find something obviously encrypted.
3) Scrub your computer, and ship yourself a copy of what you need to wherever you are going - this works pretty well so long as you actually get your shipment.
4) make whatever you need available online somewhere and just download it wherever you go. This is probably the best option so long as it's feasible for you.