I\'ve heard that Delphi\'s NEW Rad Studio XE2 has something called FireMonkey that will allow the same code to build Windows 32, Windows 64 and
Not much has been said publicly about it yet, but it looks like FireMonkey is the name of the new cross-platform GUI library, analogous to the VCL but not tied to Windows. A lot of people have been speculating that it's based on the KSDev technology that Embarcadero bought a while back, but I don't know if this has been confirmed or not. Any further details will probably have to wait until we get some official word about it.
EDIT: Looks like Andreano Lanusse just posted a bunch of official preview info about the library. See http://www.delphifeeds.com/go/s/82632 for details.
Also note - the Delphi XE2/FireMonkey product launch was in Auckland yesterday, so info is now public.
Not only does FireMonkey do native Win32, Win64 and OSX - but also native IOS!. This is huge.
If you want to make an OS X version of your app you can also take a look at FreePascal.