As you already know

My little syntax petpeeve....

There is nothing more patrionizing and absurd than prefacing information with "as you already know." I hate it! If I already know then why are you telling me.

More than likely you are telling me because I don't already know, hense the preface is uneccary.
What is behind that preface is "What I should already know," often accompnied with a tone of arrogance.

This attitude is completely in tote with the humble thanking of "each and every" often employed in speeches. Yet the audience is not null of common sense in that each and everyone can not be thanked on the individual exchange, thus it is absolutely obnoxious to assume that