ContactSync is a workaround for an issue found on some Android devices: the impossibility of Google-synchronized contacts creation. It makes all the contacts synchronized with Google.
Runs only on Android Cupcake/1.5, and can fix only the devices that have the specific contact database structure leading to this issue.
For more information on this issue, see:
Question: How do I add a google-contact in Android?
Question: contact sync issues
WARNING: phone instability has been reported on HTC Hero (it seems OK on Dream and Magic). Use ContactSync at your own risk!