Chris -- did you just break the cable or is the latch/mechanism itself broken? If it's the cable, you can work in through some of the slots of the grill with a big screwdriver and push/pull the latch towards the driver's side. You're trying to duplicate the motion imparted upon the latch release by the cable. Once you get the hood open, you can make a temporary latch release from some coathanger wire inserted into the hole in the latch (where the cable attached) which then dangles out the grill.

If the mechanism itself is broken, and this happened to me once after a front end collision, you'll have to take more drastic measures. I had luck by lying on my back under the front end, sticking a crowbar up onto the end of the hood 'spike' (what fits down into the latch), and wacking up in the crowbar with a hammer to drive the 'spike' past the latch. This isn't as painfull to the car as it sounds because the 'spike' is spring-mounted and has some built-in wobble.

Good luck.

Rob