The OOP article here is pretty nice.

I lack the teoric for­ma­tion to com­ment on it too well, but IMHO, ag­gre­ga­tion is nice, en­cap­su­la­tion is 50% nice, and deep in­her­i­tance trees tends to make life painful ;-)

Oth­er than that, not much to say to­day.