While killing the last of the Pazzi conspirators - the chap named Baronchelli, I think that you're supposed to run away after the deed is done because there are so many guards around. However, I stayed and fought them all off successfully, but when I received the assignment completed message, I noticed that the remaining guards were simply standing around in an aggressive pose, but not doing anything. I was fully notorious, and should have been viciously attacked, but even when I wandered around town, no one would take a swing at me. I was able to collect codex pages, money, and stroll completely unmolested.
wow, cool tip :) :-X
Reminds me of one eor123 posted regarding the escape from Mosate Selao through the front door instead of the back one. I don't know if this is reproducible, but it sure was fun while it lasted!