I've got a batch in the primary right now. I did quite a bit of research on how everyone added it. Some added it into the boil and had good results, some did everything in secondary, some did a mixture of both. Pureed, chopped, diced, frozen, etc. I decided to chop up two ripe pineapples, and added it with 15 left in the boil. Strained it well, and pitched the yeast.
I have noticed that the fermentation seems a bit less vigorous than usual, but I am swamp cooling this batch since my chamber is currently being used as a kegerator (time to invest in another chest freezer or fridge). It is fermenting at about 70, so we will see how it progresses.
I had planned on tasting it before moving to secondary, and will have either the frozen pineapple concentrate or the canned ready to go in case it isn't "pineapply" enough. May try the grilled pineapple to add to the secondary too. Lots of choices.
For whomever is brewing with pineapple now, please keep the rest of us posted. I'm sure it is not an exact science, but I like experimenting based on successful recipes that other's have worked out too...haha.
Cheers.