Antenna House, Inc has released XSL Formatter 4.1 for Mac, Linux, and Windows. This tool converts XSL-FO files to PDF. Version 4.1s XSL 1.1, PDF 1.6, PDF/X and Tagged PDF. New features in this release are fairly m,inor; for instance the printer tray can be specified.
The "lite" version costs $300 and up, but is limited to 300 pages per document and doesn't support right-to-left languages. Prices for the uncrippled version start around $1250. Support costs more.