The Home screen component in Apple iOS before 5 does not properly support a certain application-switching gesture, which might allow physically proximate attackers to obtain sensitive state information by watching the device's screen.
https://exchange.xforce.ibmcloud.com/vulnerabilities/70554
http://support.apple.com/kb/HT4999
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00001.html