I took 6 months off for medical reasons starting the day after I got my CFI, back in 2006. When I finally got back into it, it was like i never even took a break. As of right now, the last line in my logbook is from October 2008.
It's my opinion that the ease at which you experience in getting back into flying is a function of how well you knew how to fly in the first place, and how much aviation occupied your mind when you weren't flying.
The problem is that companies seem to be under the impression that if you don'tr have any time logged in the past 6 months or whatever, then you have lost all ability to fly and will have to be retrained a lot. I've been unemployed since early November, and I wonder how many jobs I've been not offered simply due to the face that I don't have so little recent experience.