Aside from the sheer joy that Your Boston Red Sox will be playing during the last week of October, and maybe into November(!), the World Series means that there is no Red Sox Radio Network, and thus, Glenn Geffner will be absent from the air in such places as Berlin, Putnam, St. Albans and Millinocket. See, under broadcast rights deals, the World Series radio broadcasts are exclusive to The Alleged Worldwide Leader.
The local flagship in Boston (WRKO[WEEI on Wednesdays--Game 1 and 6]) and in Denver (KOA) will have the home crews calling the game, just for that signal. The Red Sox spanish flagship (WROL) has the same deal.
So, with Dave O'Brien still doing MLB International, Joe C and Glenn Geffner will be limited to those people who can get the 50kw WRKO signal.
Of course, those feeds will be available on mlb.com.
More importantly, if you haven't had enough of Glenn yet (and who doesn't want more?), it's all on XM Radio: All three broadcasts, plus the nationwide ESPN Feed. Read about what XM has in store here and here
A caution (and I am a big XM honk), the delay between the XM feed and the TV feed is on the order of 3-4 seconds (given the number of audio legs the signal travels to get to your XM unit), so turning down Tim McCarver ("the team that scores first generally takes the lead") is not a realistic option.
However, if/when the Sox get to the clinching moment, this is a necessity (assuming they do not clinch in the 10th inning and Glennski is on the mike). In '04 I was in the desert in Northern Arizona listening on the over-the-air broadcast from ESPN in my rented car. However, when the ninth inning came around, I went back to my hotel room, and listened to Joe ("Stabbed by Foulke") on a dialup connection