I just installed a "nightly build" of firefox 3.7 that supports the html 5.0 canvas object, because apparently a version of openGL ES (the 3D stuff on iphones) called webGL is now going online, with support in firefox, opera, chrome, safari.
No plugin required.
IT WORKS!!! The frame rate is low, but there are only a few demos I've found to look at.
WebGL - OpenGL ES 2.0 for the Web
If you want to try it, click thru to the wiki.
This is pretty good news for me. Maybe less so for "silverlight"....