We're quite excited about our upcoming WPF 3.5 release which will now support seven Indic scripts!!
For those of you curious about what languages this implies, here's a mapping between scripts, languages, and fonts:
Hindi, Marathi, Sanskrit
For other new upcoming features, check out Tim Sneath's blog.
Note: Indic script support is not available in the current public Beta, it will be available in the final release.