Question
Ok, it's kind of just been part of the yard for the last 5 years.
Every year it gets bigger and bigger.. it's about 15 feet long this year and is devouring our chain linked fence.

It has a woody trunk about 5 inches in diameter, and its "branches" are long and thick and wrap around everything.

I've not noticed flowers but it has beautiful purple/blue/red/pink berries on it and tons of caterpillars chewing on it.

Any idea what it is? is it edible, dangerous, etc?

http://a3.sphotos.ak.fbcdn.net/hphotos-ak-ash4/301520_10150270296689263_62062426
http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/262568_10150270296764263_62062426
http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc7/293393_10150270296854263_62062426

Answer
I think it is  Ampelopsis cordata Common name: Heartleaf peppervine, Heart-leaf Ampelopsis, Racoon Grape, Possum Grape, Simple-leaf Ampelopsis
The fruit are not edible. It is in the grape family. Here is a web site that describes the vine.

http://aggie-horticulture.tamu.edu/ornamentals/nativeshrubs/ampelopsiscardat.htm