Following contact data gets backuped (if available):
-Name
-Contact photo
-Phones
-EMails
-Addresses
-Events
-IMs (Instant Messenger)
-Nicknames
-Notes
-Organizations
-Relations
-SIP Addresses
-Websites
-Some more general attributes
All contacts are stored on the sd-card in a XML file that can easily be used for further purposes.
All contact photos are stored as *.png image file.