While investigating the data of a Samsung GT-i9100 (Galaxy S) we found parts of SMS messages in the file: Logs.db.
The Samsung GT-i9000 runs on Android, so we expect to find the same results in other Android devices.

We found the database at: NO NAME_ 3/databases/com.sec.android.provider.logsprovider/logs.db
Logs.db was a SQlite database that can be opened using a SQLitebrowser.

In the column M Content we found (parts of) SMS messages.
In the column Date we found what was probably the date, coded in Unix-time.
In excel these timestamps can be easily converted using the formula: =(CEL/86400000) + 25569