Unlike a Hydrogen Bond, a disulfide bridge was not shown in the first implementation of FoldIt. Manipulating Cysteine sidechains so that their ends point toward one another has sometimes been noticed to yield points, but as it turns out, the developers have confirmed that this effect is unrelated to the disulfide bridge. As of the past implementation, disulfide bridges do not seem to be scored in FoldIt.
Starting in January 2012, disulfide bridges are enabled in ALL puzzles by default.
To see them click on Show bonds (sidechains) in View options (V). First get the advanced GUI iin the general options.
More information can be found at http://en.wikipedia.org/wiki/Disulphide_bridge