First, the bad news: Firefox 3 breaks some Silverlight 1.0 installations. The good news: Silverlight 2, a Beta 2 version of which Microsoft released earlier this month, works fine with Firefox 3.
Microsoft blogger Nigel Parker explained the Silverlight 1.0-Firefox 3 problem in a June 17 blog post:
"Firefox 3 has a race condition that affects the way that <object is invoked, loaded and detected.
"What this means is that the forthcoming Firefox 3 release will break some Silverlight 1.0 installation experiences on web sites that used the original Silverlight 1.0 SDK Silverlight.js detection file.
"The Silverlight 2 SDK (Software Development Kit) has an updated Silverlight.js file that not only solves this problem for all versions of Silverlight but also eliminates browser restart that was previously needed for new installs."
Firefox 3 is available for download starting today, June 17.
Silverlight is Microsoft's alternative to Adobe Flash/Flex/Shockwave and other similar technologies. It is a plug-in designed to provide support for rich Internet apps, and to work with a variety of browsers, including Internet Explorer, Firefox and Safari.
Microsoft is expected to release the final version of Silverlight 2 later this summer.
(Thanks to Winbeta for the pointer to Parker's blog post.)