Via the UEFI firmware capsule feature of UEFI 2.5 and newer, they are beginning to support updating your system's firmware in a standardized and fully open manner. Dell will support the fwupd utility developed by the Red Hat developers for Fedora and has since been picked up by Canonical and others. The new BIOS/firmware updates will be pushed to the Linux Vendor Firmware Service. Basically, it's the standardized and nice approach to updating UEFI systems and if you have a supported system it will make updates a breeze.
The first Dell system supporting this means of firmware/BIOS updating is the Dell Edge Gateway 5000. More details on this Dell firmware updating under Linux can be found via this Dell community blog post. This news isn't a huge surprise as back in December they confirmed they would begin working on Dell UEFI system updates from the Linux desktop.