I have never come across a reference for red berries (the berry is called a "drupe" - save that for Trivial Pursuit :-)) for poison ivy. In fact, one of the old wives tales goes like this:
Berries of white, take flight
The drupes of poison ivy, poison oak, and poison sumac are white or cream colored. Here's an excerpt from Outwitting Poison Ivy: How to Prevent and Treat the Effects of Poison Ivy, Poison Oak, and Poison Sumac--For Hikers Campers, Gardeners, and Anyone Else Who Spends Time in the Outdoors, a long winded title but for an interesting book. You'll see that Susan Hauser mentions in her book that the fruit and flowers don't vary much with these plants.
There are a number of other plants though which can cause dermatitis.
Did you get a picture of the offending plant? If so, I'd love to see it.