I've got a tear, too, and some questions about brakes and oil filters too.
2006 OBW, 2.5 sohc, 17000 miles.
First, the control arm tear. The tear is on the left side (haven't checked the right side yet). Regarding the theory about cold weather being a factor, I live in Southern California and have gone up to the snow just 3 times since I've had the Outback. Also, I don't think that the weather was especially cold during any of those snow trips. On the other hand, here in SoCal we have a lot of Ozone and it loves to eat rubber. I have posted a picture of the tear at: http://www.killthegoose.com/JointTear.jpg
I noticed the tear because I had the tire off to try to track down the source of a couple noises/vibrations I've heard recently. The vibration was a judder occurring on moderately hard braking from low speeds, like 25 mph. I don't have a lot of experience with abs brake systems, but it was almost like the abs system was cycling. Except that the tire was no where near skidding at the times it would do it. That juddering went on for a couple months, intermittently.
The other noise I just noticed in the last few days. A continuous, quiet, squeak. I could only hear it if I was driving slowly next to a wall that would reflect the noise back to me. My brake pads are down to about 3/16" of material left. Could that be the source of the squeak? (Any reccs as to what brand of replacement pads to use?)
I guess I will have to take it in to the dealer to have the torn rubber joints replaced. This will be its first visit to any mechanic - I've been doing the oil changes, etc., myself. I have a question about that too. I've been using oil filter Purolator 14410 and notice that all the catalogs now list 14610, which is TINY. Every other brand also lists the tiny filter. Would be big (old) one be preferable, if I can get it?