Passcode Lock in Apple iOS before 4 on the iPhone and iPod touch does not properly handle alert-based unlocks in conjunction with subsequent Remote Lock operations through MobileMe, which allows physically proximate attackers to bypass intended passcode requirements via unspecified vectors.
https://exchange.xforce.ibmcloud.com/vulnerabilities/59633
http://www.securityfocus.com/bid/41016
http://support.apple.com/kb/HT4225
http://lists.apple.com/archives/security-announce/2010/Jun/msg00003.html