I recently blogged about using navigator.plugins.refresh() to help make the installation experience a happier one for people on Firefox and Safari. Well according to Jamie Rodriguez on his blog, this will be baked into the next version of the silverlight.js file.
This will be great. Rather than building your own script to check every 5 seconds if Silverlight has been installed, you can rely on Microsoft doing it for you. That way you can utilize their QA department to test it and all you have to do is update your silverlight.js file.
The added benefit here is that since Silverlight 2.0 is 100% compatible with Silverlight 1.0 (it is actually a superset of features from 1.0) you can take the 2.0 version of silverlight.js and use it on your Silverlight 1.0 site!