Only Windows; I don't think Lee has any experience with Linux/Mac/Other development, and it would be alot of extra work for such a small market.
Perhaps if Linux / MaxOSX ever got as popular as Windows.
Right now it's just not economically sound to support or atleast keep upto date other Operating Systems with retail products, unless that is where you main markets are.
Look at PureBASIC, Fred keeps the Windows version constantly updates, but Linux and AmigaOS fall behind; and he is soon to introduce a MacOSX version too, with 4.0 hopefully all versions will be equal but the problem is time.
Most other systems you can expect people to make Basics/Products for are mostly the Sourceforge or people who do it in thier freetime rather than professional products.