SQL Server 2008 can generate compressed database backup files in the Enterprise Edition, while SQL Server 2008 R2 introduced that feature in the Standard Edition.  Do you then need 3rd party compression backup software?

I guess it pretty much depends on whether the value added features provided by those software is worth the extra cost to you.  Since I work daily on Red Gate's SQL Backup product, I'll touch on some features available in that product, that goes beyond just compression.

·Restoring a chain of transaction log backups

·Restoring to the latest possible state

·Backing up multiple databases

·Backup retention

·Making a copy of the backup file

·Backup file naming conventions

·Restore using the latest backup set

·Network resilience

·Encryption

New in SQL Backup version 7:

·Integrated database verification

·Database file relocation

·Improved backup retention

·RESTORE HELP

New in SQL Backup version 8:

·High-availability group support