I'm reminded most strongly of this statement from one of PG's essays: "...eventually the open source world won, by producing Javascript libraries that grew over the brokenness of Explorer the way a tree grows over barbed wire."
It's amazing to see this happen for non-javascript issues as well.
This is a prototype: "Mozilla's Vladimir Vukićević has developed a working prototype which demonstrates the viability of the plugin approach... There are still some missing pieces, however, including support for several drawing functions. It's still largely a work in progress, and development is still at a somewhat early stage."
"Mozilla might drag IE into the future with Canvas element plugin" would be more apt.
The notion that this needs to be a plugin is mistaken. There are several apps out there that built a compatibility layer on top of VML in JavaScript and do it with plenty of speed. The author himself notes Google Maps. 280 Slides does the same thing.
VML and Canvas provide very different APIs and behave very differently. Explorer Canvas maps the Canvas API onto VML with very poor results. It may be possible to build a library that uses either Canvas or VML but they're so different I almost think it'd be easier to target each separately. Either way, this is a non-trivial pain in the neck.
It's amazing how desperately people want canvas compatibility in IE. It's such a simple API, too. It's hard to imagine that it would take any real resources for Microsoft to create a nice, fast implementation. But, once again they seem to prefer holding the web hostage.
You're right though, it seems unlikely that a plugin will succeed. But, the fact that someone's working on creating one is more proof of how lacking the other workarounds are and how much people want this technology.
There are a number of folks who can't install plug-ins because their machine is locked down or won’t because whoever the family friend is who cleans up their PC messes has successfully drilled into their heads the "just say no" mantra for whenever a security prompt rears its ugly head.
I applaud Mozilla for doing something that will make Canvas more universal but I am afraid that for really horizontal applications using one of the compatibility layer libraries is the only sensible approach. Do you really want the first impression of your app to start off with a security prompt?
"Mozilla is working on a much more ambitious initiative called Screaming Monkey that will make it possible to plug Mozilla's entire next-generation JavaScript engine directly into Microsoft's web browser."
It's amazing to see this happen for non-javascript issues as well.