INF/autorun is USB malware (aka – a USB virus) that is automatically installed to your PC via an autorun.inf file. Since USB drives are so popular these days most of the new malware released also copies itself to the USB flash drive and waits to travel to a new PC.
The USB malware threat is somewhat overblown. Most antivirus programs can easily detect and clean USB flash drive viruses as long as the anti-virus software is up to date, however as we all know, not everyone runs anti-virus or keeps it up to date.
For more prevention, consider running a Host Intrusion Detection program along with your anti-virus (like Threatfire). HIT programs can easily prevent USB viruses from auto-installing and HIT doesn’t need to be updated as much as anti-virus software.
I personally have come into contact with a USB virus (from my wife 
) and it was easily killed via Kaspersky.
