Gmail now with antivirus scanner

Gmail just launched its new feature for gmail users : virus scanner for attachment. The feature works this way:

1. Each time we send and receive attachments , gmail will scan them for viruses.
2. If it is found in an attachment we've received, the system will attempt to remove it, or clean the file, so we can still access the information it contains.
   
3. If the virus can't be removed from the file, we won't be able to download it.
4. If a virus is found in an attachment we're trying to send, we won't be able to send the message until we remove the attachment.

Although I never encountered any viruses attached to emails sent to my gmail's account (maybe they were running some sort of virus scanner before to filter attachments to /dev/null :) ), I still think this is important feature for gmail's users because some users don't know that their files has been infected by virus(es) and then they send it to their friends without knowing it.