Adding chili peppers to beer - when?

I've had great luck making pepper extracts with vodka and adding them shortly before bottling. Soak for a couple of days, then either pull a measured sample of homebrew or a find a similarly styled commercial beer and add measured quantities of the extract to taste. Then just scale up to your batch size and add to the fermenter. I did this with an imperial stout to add a slight burn to the finish and it turned out great.

I would maybe add your hottest pepper to the boil. That way you aren't adding alot of vegetal matter to the boil. Sort if like using a high alpha hop.

Then, I'd make a relish or mash of your less intense peppers and add that in secondary. Sort of like dry hopping.

I would also consider serving this beer out of some poblanos if you can find some big enough ones to hold say 4 oz. It would be a super cool way to sample the beer with friends. I'd just cut the top off and pull out the seeds and ribs. Then stand them up in whiskey tumblers or something like that. Then you'd get some super fresh heat and even pepper aroma. Sort of like using a randall!

I've always just added chilies straight to the secondary. I've always used roasted anaheim peppers that i just toss into secondary, and never had any problems with infection or anything. They don't add a lot of heat though, if that's what your looking for. Then again, they're really mild. They contributed some incredible flavor though. I did about 5 average sized roasted anaheims for five gallons.