Absolutely. In order to avoid any site breakage following the release of IE7, I (as part of a UK local government body) chose to employ the script rather than rely on hacks. Performance hits are negligible, and the sites we've used it on have been functioning just fine across IE 5 & 6, 7, Firefox & Opera (PC and Mac) and Safari. Which is the whole point about standards, of course.

Rather than comment on Microsoft's efforts, I'll stick to the point and say that Dean's script, whilst not perfect, certainly does a stellar job for most purposes. In fact, the only issue I've had with it was related to its use in tandem with style switcher scripts in IE 5 & 6 - reproducible, spectacular crashes on a number of different machines.