I think you meant Fallout 3 rather than Oblivion, funny mistake that.
I have heard however that the special attacks are supposed to have special results. Knockback, knockdown, that kind of thing.
No mistake, I certainly meant Oblivion which, as we all know, is based on the same engine as Fallout 3 and Fallout: New Vegas.
Thing is, melee combat had the potential of being a big part of Oblivion. With a few mods, it was just that. Deadly Reflexes added special attacks that actually took some skill and timing to use.
When Fallout 3 was made, the melee combat turned out to be crap, absolutely the worst part of the game.
I'm not all that optimistic that New Vegas will remedy those problems, unless Obsidian employed the maker of Deadly Reflexes to fashion a new melee system. As things go, it's most likely that New Vegas will have special attacks that require little or no skill and/or timing, since melee tends to take a back seat when guns are involved.
I wish I would be happily surprised, but I'm not holding my breath either.