A user named narf2006, a reputable Mac hacker on the WinXP on Mac forums, has been able to get Microsoft Windows XP SP2 running on his Intel iMac, as noted by ArsTechnica and his revealing flickr stream. He has given some detailed instructions to the contest holders and is under review for the 12,000 WinXPonMac contest prize. If this turns out to work, it would be a breakthrough. I would dual-boot it on my Intel Mac Mini, for those times when I absolutely must run an application such as a certain C compiler in Windows. I donated to the contest when it first started and it's good to see that there might be a solution.
Of course, immediate reaction tends to be "zomg Photochop lol!" And I won't say that that wasn't my initial reaction either. However, upon further inspection of the currently available evidence, there may be more to this rumor than mad chops. A post titled "Mission Accomplished - twice almost" on the Windows on Mac blog appears to indicate that narf2006's processes are (almost) reproducible and there is even a thread on the forums now asking for testersâ€”three for MacBook Pros, three for iMacs, and three for Mac minis.