While this isn't a Maia bug, it affects Maia users wishing to use PHP 5 and IMAP authentication. The bug and its solution are described here.
While this is likely to be fixed in future versions of PEAR::Net_IMAP, it plagues the current version (1.0.3), so a one-line patch for the IMAPProtocol.php file is all that's required to get it working with PHP 5. We should provide that patch with Maia until such time as a new release of PEAR::Net_IMAP is issued.
Furthermore, we can detect this condition within configtest.php--the combination of PHP version >= 5 and PEAR::Net_IMAP version == 1.0.3--and warn users to apply the supplied patch.