I don't see how this will make much of a difference in the end really. Sure you've opened up Steam as an available service to buy your game, but with all the bad press from within the local Unreal community such as us, and the Unreal forums themselves (deleting threads etc, is not the simple fix to things, it's shoving complaints under the rug), I don't see why PC sales will increase.
Sure, some people may buy it because it includes many other games with it, but come on, seriously? It only serves a two purposes for me.
a) It's pissed me off because I bought UT3 for $110 NZD. i.e, I bought it when it was occupying shelf space. Games eventually shift to low price games, but not within this timeframe (unless they are really awful).
b) Please, do not include this within the sales figure of UT3.
At the end of the day, I don't see why people would nibble at this other than the fact that it comes with other Unreal games. I doubt people are buying this pack for UT3 alone.