http://developer.apple.com/iphone/library/qa/qa2009/qa1649.html
Excerpt:
You are getting this warning because you probably added your Info.plist file to your Copy Bundle Resources build phase as shown in Figure
[figure shown]
The INFOPLIST_FILE build setting specifies the name of the Info.plist associated with your target. When building a target, Xcode reads this build setting and copies the referenced Info.plist into your application bundle. Because Xcode automatically processes the Info.plist, you should not add it to your Copy Bundle Resources build phase or make it a target member.
To resolve this warning, select your Info.plist from the Copy Bundle Resource build phase as shown in Figure 1, then click the Remove (–) button to delete it from the phase.