There was a thread about this subject back on 23 Oct.; the OP felt that there was a firmware glitch because the D800E had to be set to at least 2 in order to trigger a bracket sequence. The D7000 self-timer can be set to 1 shot and it will fire off a complete bracket sequence.
Also, if you set your self timer to 5, for example, and set your bracket to 3 shots, the D800 will only fire off the 3 bracket shots and then stop.
Your D90 has this feature as well, however, the number of shots set on the self-timer has to coincide with the number of bracket shots you set.
I do not know if it is available on the D300/s, I couldn't find it on the D700. Ciao.