From the ever-popular Life In The 20th Century Department:
In Macs and Grant Site Just Don't Click (registration required), Washington Post Staff Writer Rick Weiss reported on September 13 that a major Federal Government-wide electronic grant submission system operated by Department of Health and Human Services requires a Windows computer to access the web site, Grants.gov. This makes it difficult for some grant applicants who use Macintosh computers to apply for grants online.
Based on interviews cited in the article, a revised system accessible to Macintosh and Linux computers is currently under development and might be available early next year (2007).