Here is an article from 2004 that gives some insight to the postgame handshake:
http://mlb.mlb.com/news/article.jsp?....jsp&c_id=null
As a fan of the game and sportsmanship, I loved it as well. I remember reading some follow-up in the St. Louis paper afterwards (Post-Dispatch) that the execs at MLB weren't pleased with the moment as it went against MLB's non-fraternization rule. I wish I could find that article now...
Here's another piece that speaks to my comment above. Take note of the final few paragraphs:
http://query.nytimes.com/gst/fullpag...pagewanted=all