This has created a small tempest of protest from those users still using XP, but this is less of an arbitrary decision than some appear to think. It's literally impossible to port Windows Vista/Win 7-style hardware acceleration backwards into XP. Microsoft would have to either develop a workaround from scratch or create a CPU-driven "software mode." Using such a mode could easily max out a CPU and negatively impact system speed and battery life.
So, yeah, that's what we call an improvement, particularly when compared against IE8.
We also don't think much of the argument that Microsoft is abandoning XP lovers. IE8 is much more secure than IE6 by any comparison and while XP is still humming along on an awful lot of netbooks, consistent sales data has shown that netbooks are almost always secondary systems, not primary ones. XP and IE8 are fine for a netbook, especially since it could be 6-12 months before we even see IE9 ship. After nearly 10 years it's time to let XP totter off and die with dignity.