I imagine it will be fixed. IE8 actually uses, wait for it, W3 standards. Yes, that's right. After decades of wandering around with their heads up their butts the IE dev team was finally convinced to build IE8 along the same lines as every decent browser in the world today.
Mind you this only happened late in the development of IE8 and it only happened after the IE team announced that IE8 would use the IE7 standards, which of course are not W3 compliant. This announcement caused such a massive uproar, and such vehement condemnation from so many people around the world, that the IE team actually found the brains and guts to admit it was a terribly dumb idea. Amazing. I wouldn't have thought it was possible, and it's about time too.
What it means though is that anything coded to detect IE will attempt to apply corrections for IE's previous pestilential standards. This obviously will mess things up a bit in IE8, which is why the compatibility mode was included. In other words, it's Microsoft's f@#kup, not anyone else's.
Now that they have sorted themselves out I expect that sites, and software like SMF 2, will be recoded to suit. I'm not one of the devs but I think this is obviously what they would be planning to do, and browser sniffing isn't a big deal, so I would expect it would be sorted before Final even if it isn't sorted by RC2.