We are having some significant issues with IPhones eating up all available connections since the upgrade to iOS4. We are in the process of getting end users to patch their devices as Apple has released a patch for this already. If you are having some strange runaway processes on your system that max out your available wireless connections (set in /var/opt/scalix/XX/wireless/wireless.properties) and max out your IMAP connections, this may be something to explore.
The patch can be found at the following:
http://support.apple.com/kb/TS3398
FYI