I'm in the process of doing a chocolate cherry porter, things I have observed are:
-Cherries in the primary can cause fermenter explosions(fresh cherries and canned cherries with do this at different speeds as well, fresh cherries will blow up between 8-16 hours and canned will do so anywhere from 4-24 hours)
-Cherries in the secondary can restart fermentation and give you a yeast cake again
-Less than 1lb of cherries per gallon only adds a hint of cherry flavor
-I've seen it recommended that you freeze the fresh cherries first to break open the cells
-Instead of adding them to the primary after you use yeast I've seen it recommended that you add them to the brew pot when you do flame out at the end of the boil and let them steep about 15 minutes before cooling the wort
-Some people say freeze the fruit and then thaw and heat to 160F before they add it to the secondary some simply ignore it because of the alcohol already present in the beer
My 2 cents
EDIT: I only note those times because unless you use the blowoff methods mentioned on these forums you should watch it and release the pressure manually
I split my cherries in half with 2lbs in the primary 2lbs in the secondary...
DOUBLE EDIT: I added a few lines... I wish this had all come to mind when I was writing the first list
Cherries can do this:
