Developers seem to be having quite a few problems trying to integrate the latest versions of OpenFeint (2.8, 2.9) with their Unity 3 iOS games. See the following for some discussions of the problems:

Unity Forum: OpenFeint-iOS-2.9-problems
Unity Forum: my-iPhone-application-is-getting-crash
Answers.Unity3d: crash-at-first-launch-with-openfeint.html

To save time as I try to put out a bug-fix for Pawns, I decided to stick with OpenFeint 2.7.5.

However, I ran into some of the problems people had with later versions of OpenFeint. Specifically, the app was crashing with one of the following errors when I closed the OpenFeint dashboard to return to the game:
mi_cmd_stack_list_frames: Not enough frames in stack.
or:
[CAMediaTimingFunctionBuiltin deactivate]: unrecognized selector sent to instance

So apparently the upgrade to Unity 3.3 and/or iOS SDK 4.2 is where this problem started, not because of changes to OpenFeint. The solution, as reported by developers using later versions of OpenFeint, was to comment out calls to UnitySetAudioSessionActive in the dashboardWillAppear, dashboardDidDisappear methods in AppController+OpenFeint.mm:

// OpenFeintDelegate //
- (void)dashboardWillAppear
{
	unityPaused = YES;
	//UnitySetAudioSessionActive(false);
	UnityPause(true);
}

- (void)dashboardDidDisappear
{
	unityPaused = NO;
	//UnitySetAudioSessionActive(true); 
	UnityPause(false);
}

Another symptom I noticed was that when my game was exited under iOS 4 and then brought back to the foreground, the game would appear but then immediately quit (though iOS still listed it as running for some reason.) Bringing it forward a second time would basically run it over from scratch. I concluded that it was crashing on resume, and the culprit was the same call to UnitySetAudioSessionActive, this time in two other delegates. Commenting those out fixed the issue:

- (void) applicationDidBecomeActive:(UIApplication*)application
{
	printf_console("-> applicationDidBecomeActive()\n");
	
    if (gDidResignActive == true)
    {
	    //UnitySetAudioSessionActive(true);
	    UnityPause(false);
    }
	
    gDidResignActive = false;
	
	[OpenFeint applicationDidBecomeActive];
}

- (void) applicationWillResignActive:(UIApplication*)application
{
	[OpenFeint applicationWillResignActive];
	
	printf_console("-> applicationDidResignActive()\n");
	// UnitySetAudioSessionActive(false);
	UnityPause(true);
    gDidResignActive = true;
}

The fact that this problem apparently persists in OpenFeint 2.8 and 2.9 isn’t good. I get the distinct impression that OpenFeint’s Unity wrapper is not very well supported.