I don't believe this has been officially announced but I found it on ESPN listings
It is not yet listed at Cubs.com but I first noticed today on Yahoo which I certainly would not trust but it is now listed on ESPN.com
NOTE FROM AL:
Just got an email from the Cubs confirming that 8/10 vs. St. Louis WILL be the ESPN Sunday night game beginning at 7:05 CDT.
Also, Monday 8/4 vs. Houston has been picked up by ESPN -- game time changed to 6:05 pm CDT. I'll post this in the pregame thread for tonight, too.