I've recently installed a couple of Belkin Wemo WiFi enable light switches, some of which control outside lights on the house and looking to get them tied into a driveway alarm currently installed.  The driveway alarm has a 12VDC output that is enabled when the alarm is triggered and can be hot for either 3 seconds or 10 minutes.  What I'm looking for is a easy way to take the 12VDC output from the driveway alarm to a web trigger that I can use with IFTTT to automatically turn on the exterior lights for a set amount of time.  I'm pretty new to the home automation stuff so looking for some ideas of what the cheapest/most effective way to accomplish this would be, I've got an ok understanding of electronics but would prefer to not wire up an Ardunio if possible as I've got plenty of other projects on my to do list and an Ardunio project would probably kill way more time then it should.

Where is the driveway sensor trigger located? In your house, or somewhere outside?

You are probably going to need some way to convert the relay activation into a usable signal, and a network-connected microcontroller would seem to be a pretty good way to do it.

But I don't think that a regular Arduino will do the trick, since out of the box a typical Arduino will not talk to a network.

There are specialized Arduino clones (or network add-on cards for Arduinos) that you would need to use.

I've recently started playing with a $30 Texas Instruments CC3200 Launchpad which would do the trick (and there is Arduino-compatible development software for it).

The main controller portion of the driveway alarm that includes the 12VDC output is in the house so has easy access to power, WiFi etc.  I'll have to take a look TI and see what I think, thanks!