There are several good solutions.
If you talk to someone like Jack/Guy/Mike they'll tell you that you take your laptop, 3 harddrives, and back everything in triplicate. Then each person carries just one hard drive
Myself, I use a portable media player (PMP). It has slots for SD and CF I/II. I pop in my cards, and copy the images over to a 60 GB hard drive. Unfortunately my unit is over 2 years old and it's getting a little long in the tooth (which is to say it connects to my computer via USB 1.0). It's not a big deal and it works well, so I still use it.
NOTE: This places all previous images on one harddrive with NO backup. I lose that drive, I lose ALL my images. Knock on wood, this has never happened to date.
Epson makes units as do several other manufacturers and most (if not all) use USB 2.0 now. They've also increased the download speeds from the CF cards to the units themselves.
A NON-HARDDRIVE solution is to burn discs as you go. Most developed areas have areas to stick in a memory card, and burn a DVD disc. I have friends that rely completely on this method. They burn 2 of everything. They drop one in a mailer, and mail it home; and carry the other one with them.
I've talked to them and told them that if they were really paranoid, they could burn 3 copies. Mail the first one right away, and mail the 2nd disc when they need to burn off another set of discs. This way, if anything got lost in the mail, they'd have a second copy being mailed to them. And they'd always have that last disc with them.