As if the legitimate issues regarding selecting too much data, etc., weren't enough....a comment from a different perspective. I seem to recall a few years ago that there were a few databases (vendor-wise) that didn't respond correctly to the select *. Sometimes they returned all of the data, sometimes not. If I remember right, this was a flaw in Microsoft SQL 7 server (yeah, yeah, yeah, we all have our burderns to bear). In addition, though, I have on occasion seen select * not return all of the columns. Sporadic, non repeatable, I know, but the lack of perfect success leads me to suggesting that you should avoid select * whenever possible.
Not to mention the load once your database starts getting to a decent size...