I knew when RC1 was released that they planned to have both versions available. In fact I remember commenting on that some time back. When you start seeing a large number of new games come out that will run on the 64bit versions of Windows that will indicate the trend is then moving away from 32bit. At the present time we are all locked into 32 games and apps even with the 64bit versions of XP and soon Vista coming out.
The other problem remaining currently is the total clearout of 32bit model cpus and hardwares. While gamers and custom builders in particular are always ready to grab the latest 64bit supported there are too many businesses, schools, hospitals, you name it running older systems. Those are also a large part of the software market.