In some ways the Elfa Shelf system is just like the slotted shelf standards you can get at any hardware store, but in other ways it is not. First off, its a double slot system. Easy shelf bracket slides into two sets of slots and this gives the brackets much more strength side to side. Second Elfa can be wall mounted, but it can also be freestanding with legs, or hung from a top rail which really speeds and simplifies installation.
As far as being suitable for a vertical desk configuration, they offer brackets for shelf depths up to 24" deep which is perfect for the desk height shelf of a vertical desk system. Their brackets are triangular however, but they are less deep than other systems. It should be possible to use a mobile table underlapping the shelf without it needing to be too low.
Here is a freestanding installation, with legs and poles rather than wall mounted standards.
And another office set up using the hanging rail.
Here is a home office set up using Elfa posted at the Unplggd blog.