You can sync contacts and calendars using either Funambol or CardDAV/CalDAV.  The latter protocols are built-into most mobile devices including iPhone.  Below are instructions on using CardDAV/CalDav for synchronization.

Configuring CardDAV
Follow these steps to set up CardDav on the iPhone or iPad:

    Open the settings application.
    Tap Mail, Contacts, Calendars.
    Tap Add Account.
    Tap Other as account type.
    Tap Add CardDAV account.
    For server, type yourdomain.com
    Enter your full email address for User Name, and then type your password.
    Tap Next.
    A SSL warning will be displayed. Tap Continue.
    If the iPhone is unable to verify the account information perform the following:
        Tap OK.
        Tap Advanced Settings.
        Make sure Use SSL is set to OFF.
        Change port to 80.
        Go back to account information and tap Save.
    Your contacts will now be visible in the Contacts application (if the contacts are not displaying, ensure you have your device set to list All Contacts, or, you can select to show only contacts from the webmail account)

Configuring CalDAV
Follow these steps to set up CalDav on the iPhone or iPad:

    Open the settings application.
    Tap Mail, Contacts, Calendars.
    Tap Add Account.
    Tap Other as account type.
    Tap Add CalDAV account.
    For server, type yourdomain.com
    Enter your full email address for User Name, and then type your password.
    Ta[ Next.
    A SSL warning will be displayed. Tap Continue.
    If the iPhone is unable to verify the account information perform the following:
        Tap OK.
        Tap Advanced Settings.
        Make sure Use SSL is set to OFF.
        Change port to 80.
        Go back to account information and tap Save.
    Your calendar will now be visible in the Calendar application