On ESPN, there is a poll being done regarding which interleague rivalry is the most anticipated. As it stands right now the Mets-Yankees series is in the lead:
                             
ESPN definitely does its part to hype the NYC rivalry, but these reults make sense to me considering Yankees & Mets fans seem to be spread out throughout the country. However I definitely figured the Cubs-White Sox matchup would rank higher...there must be  a lot of Red Sox fans because I know the Braves fans aren't tilting the scale.

Geographically, the Subway Series is ranked as the most anticipated in the most states as well:


Here's a good take on interleague play by Bob Verdi at ChicagoSports.com.