Initially it seemed as if this whole combat log thing would not interfere with the working of my addons. Then as 2.4 went live I realised I was wrong.
PetInfoFu reads the combat log to figure out pet happiness and to catch heal spells. SkillsPlusFu reads the combat log to figure out whether you create items, such as refined rock salt.
I spent quite some time trying to figure out how to catch the new combat log event and how to actually interpret it. Much of my search was helped by browsing through the Recount code and a fair dose of the old Trial & Error got to to a point where at least PetInfoFu seems to be working (apart from a weird random bug where it feels UnitName("pet") returns a boolean).
SkillsPlus is on my list to update next.