I have also tried it and cant get the check mark to stay on mlb 2011. When i hit the home button to get out of the fake locater app and then reopen the fake locater app the check mark is gone. I hope they can fix this before the baseball season starts. The old fake locater worked fine on my iphone 3g running 3.1.2. Now I have a iphone 4 4.2.1.
I think the dev pushed out a silent update to 1.4-1...? It seems to be working fine for me currently, but when 4.3.1 first dropped, I tried it and it wouldn't even install... I'm not even sure if dev's on Cydia can push out a silent update? However, if you look in Cydia, under the FakeLocation App in "Live Download Stats" you'll notice a listing for 1.4-1 that says 0MB (at the time of this post). Thats what makes me think "silent Update", but all I can say is it is working for me currently.