The latest Community Technology Preview (CTP) test builds of Microsoft's Windows Presentation Foundation/Everywhere (WPF/E) product went live this week. As of this build, Microsoft is supporting, for the first time, the Firefox on the Mac.
WPF/E is, in Microsoft's words, "a browser enhancement module that enables browsers to render rich content in addition to HTML." Microsoft officials have said that WPF/E will support IE 6.0, 7.0, Firefox 22.214.171.124+ and 2.0+, and Apple's Safari, among other browsers.
No word yet on when Beta 1 of WPF/E will hit. Maybe at Mix '07 in late April?