One word answer: nothing.
One of those other blogs hyperventilates about today's announcement that the WB Network, whose shows are carried on WGN; and UPN are both shutting down to be replaced by a new network called "CW", whose shows will be carried by Tribune Co. and former UPN stations owned by CBS (all part of CBS' parent, Viacom).
The post claims that the Cubs are "gradually increasing night games". Well, if "gradually" means three more games this year than last, one more than that in 2007, and then home night games are capped at 30. Total night games in 2006 amount to half the schedule, 81 dates as of this writing (there may be one or two more added later). For comparison's sake, the 2005 schedule had 79 scheduled night games. Big whoop.
Further, the post implies that there's "content to be shown in the evenings, starting at 7 pm Central time", which would bump games off WGN.
WGN has been carrying WB Network programming in this time period for several years, and a number of years ago reduced the WGN-carried games from about 120 to about 70 to 75. There's no reason to think it'd be any different in 2006 or beyond; at least, not based on this announcement.
It's wishful thinking, and I do not believe this is any prelude to any sale of the ballclub.