I also find mQuickDo hugely useful without any need for Backgrounder, which I fear may have more of an impact on battery life (though I haven't really tested).
I've found that just using mQuickDo for pure app-switching is the best thing about being jailbroken. The fact that I let it launch my five favorite apps from a 'standing start' rather than from a backgrounded state has little to no bearing on their speed of launch.
Dturner...just do it already! lol...geeewhizz. mQuickdo and SBsettings and Categories are my fav apps. Love the quick launch and not having to swipe through all the app pages.
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Iphone 3GS 32gb, Future Nokia n900 (preorder)