Microsoft’s official IEBlog notes that the final IE8 is already being distributed via Automatic Update to users with earlier beta versions, and will shortly be rolled out as to most Windows users. Microsoft typically rolls outs these updates by region to minimise server impact, so there’s no telling straight away how soon you’ll see it in your suggested update list.
If you’re a dedicated Firefox user (and the majority of Lifehacker readers are), then you don’t need to panic about getting overloaded with IE bloat: the update is optional, and you have to explicitly give your consent before it’s installed. IE8 does have some interesting new features though, such as surprising search tools and neat Windows 7 integration. Of course, your experience may vary a lot depending on which sites you regularly visit.