It's unfortunate for the users who have spent extra $400 and already bought 27 inch new iMac with 3 TeraByte fusion drive because it doesn't support boot camp for Windows installation. Users who specially love to use Windows operating system for gaming and running compatible business applications must be upset with not having this feature. As discusses earlier, fusion drive is a combination of a traditional Mac HD and a SSD to increase the overall performance of the system by leveraging the benefits of cache implementation and faster read/write in SSD's.
It's even not a fault of Apple because the issue is not with the whole new iMac but is with the 3TB drive itself because the boot camp supports the drives only upto 2TB. With the announcement of fusion drive, Apple said that “Boot Camp Assistant is not supported at this time on 3TB hard drive configurations”. The statement also means the Apple is working on making the boot camp compatible with the drives over 2TB.
So, ultimately, the statement says that people who make use of boot camp to install Windows should not fear of buying the new iMac with 3TB fusion drive because Apple is working on that. Till some extent, Apple is also right, because till now it isn't possible to Install the latest Windows 8 operating system on Boot camp, at least there is no official support on this. So, the people who love Windows must be willing to try out Windows 8 and they will need a separate PC in both the cases. However it is possible as experimented by arstechnica on iMac 2011 and MacBook Air.
However, still there are chances that this unfortunate thing for the early new iMac adopters will turn into fortune when Apple will release an update for supporting Boot camp on new 3TB fusion drive.
So, don't get upset, just explore the new 3TB fusion drive iMac until it fall in love with Boot Camp and support for Windows 8 installation.