Google let Microsoft off lightly
Back in the 90's, when the web was young and Javascript was primarily used to make clocks follow your mouse pointer, it was quite common to encounter web sites that required the user to download and install extra software in order to view them.
I can't understand why Google didn't do this with Wave. If Wave truly is the next major milestone application on the Intarweb, just like Twitter, Facebook, and Youtube before it, why didn't they stick up a big notice (to I.E. users) saying that it only works in real browsers, with big, colourful links to Firefox, Opera and Chrome's official sites, trusting that Wave itself would be desirable enough to be worth the download.
Perhaps The Register could collar someone at the big-G and ask them *why* they chose the Chrome Frame route instead of the far-less-controversial: "Get a Better Browser" route, for Wave.
I agree with Mozilla's opinion - Chrome Frame isn't good for the web. As long as Chrome Frame exists, it is not possible to steal I.E.'s market share by releasing a killer-app that only supports real browsers.
Honestly, I think we should be hearing a resounding "Phew" from Redmond. If Wave truly is all it's hyped to be, Google let them off lightly.