Q: Does XST support Verilog 2001 or SystemVerilog?
A: Initial support of Verilog 2001 was included in the 5.1i release. XST now supports all but one (configurations) of the synthesizable features of Verilog 2001, and all these newly supported constructs are documented in the XST User Guide. Xilinx will continue to expand Verilog 2001 support with each new major and minor release of the software.
SystemVerilog is not yet supported by XST.