First of all, no, ColdFusion is not yet supported on 64-bit Windows. And I don’t have a date for when it will be.
But, ColdFusion MX 7 can indeed run on 64-bit Windows (I have been doing so for a long time now). The trickier part is getting ColdFusion to talk to 64-bit IIS 6 (which by default only talks to 64-bit apps and connectors).
A Microsoft document entitled Configuring IIS to Run 32-bit Applications on 64-bit Windows (IIS 6.0) explains that Windows Server 2003, SP1 enables IIS 6 to run 32-bit Web applications on 64-bit Windows using WOW64 (the Windows-32-on-Windows-64 compatibility layer), and provides the instructions needed to enable this functionality.