Question : Does performing a SQL full backup truncate and shrink log files?

I know that executing a backup with truncate_only statement and backing up a log file can, but will performing a SQL full backup truncate and shrink log files?

Answer : Does performing a SQL full backup truncate and shrink log files?

Sure.  A database in full recovery mode allows for full backups, transaction log backups, and differential backups.  A log chain is kept internally by SQL server so that you can restore to a point in time.  A full backup does not break this log chain.  Committed transactions are not purged from the transaction log unless a transaction log backup occurs....which you cannot create unless a full backup has been created.  The full backup contains all data from the database files, along with all data from the transaction log files.  

IMO, there really isn't an advantage to keeping the transaction logs that have happened prior to the last full backup, as in the full backup you will have all of the necessary information.

Here is an article that explains it better than I can.  :)
http://msdn2.microsoft.com/en-us/library/ms190729.aspx

HTH,
Tim