The Cubs aren't permitted Friday or Saturday night home games... except during the postseason (guess we won't have to worry about that for a while), or when those games are broadcast on a national TV network.
Fox-TV has started doing Saturday night regional telecasts the last couple of years -- you might remember one particularly miserable May Saturday in 2011 where the Cubs and Giants were forced to slog through six innings in a pouring rainstorm so Fox could get its commercial allotment in. (The next day, the Cubs postponed their game against the Giants even though it didn't rain much that day.)
Anyway, here are the games selected by Fox to feature on Saturdays involving the Cubs, along with the scheduled starting time (all times Central).
April 13: Giants at Cubs, 12:O5 June 1: Diamondbacks at Cubs, 6:O5 June 29: Cubs at Mariners, 6:O5 July 13: Cardinals at Cubs, 6:O5 August 3: Dodgers at Cubs, 3:O5 September 7: Brewers at Cubs, 12:O5
You'll have to slog through one more year of regional blackouts before MLB lifts the out-of-market Saturday blackouts for MLB.TV and Extra Innings subscribers in 2014. (That still doesn't address the issue of non-Saturday blackouts, Bud. Get on it, will you?)
Here's the complete Fox schedule for 2013 so you can figure out whether you're likely to get the Cubs game in your market on the six Saturdays the Cubs are scheduled. Teams can make a maximum of nine Fox appearances per season, so you can see how the Cubs' poor play last year affected their national exposure.