It’s not always clear that OggSync is actually two different programs.  One program that runs in your system tray (OggSync for Outlook 4.20) and another program that will run on a Windows Mobile device (OggSync for Windows Mobile 4.19).  You may wish to use different ones depending on the use case you are wanting to solve.  Here are a few configurations you can use OggSync for:

1. Syncing your Outlook 2003/2007 to Google Apps (OggSync for Outlook)
2. Syncing your Windows Mobile Phone to  Google Apps (OggSync for Windows Mobile)
3. Bridging your Exchange Account with your Google Apps Calendar/Contacts via your PC (OggSync for Outlook)Microsoft Exchange <-> Outlook <-> OggSync <-> Google Apps
4. Bridging your exchange Account with your Google Apps via your PhoneMicrosoft Exchange <-> ActiveSync <-> Windows Mobile Device <-> OggSync <-> Google Apps
5. You can also use the same license for multiple PCs and Phones:Home PC <-> OggSync for Outlook <-> Google Apps <-> OggSync for Outlook <-> Work PC

OggSync is a powerful sync tool that can be used to connect all your devices to your Google Apps account as well as enable access to your Exchange information and have it available on your Google Account.