You can also cat /sys/class/dmi/id/bios_version without having to run dmidecode as root.
/sys/class/dmi/id contains also other interesting files:
- bios_date
- bios_vendor
- bios_version
- product_family
- product_name
- product_serial
- product_version
A quick overview of them all can be obtained with
head /sys/class/dmi/id/*
(I use head because it prints the name of the file above the first few lines of the file contents.)
