I'll assume this site (DNN) is using the new FCK Provider since I am currently using Chrome to make this post and the rich text editor is working for me.
At any rate, one thing to think about is how will the world change when XHTML compliance moves from "transitional" to "strict" as the norm? Seems to me these other browsers (Opera, Safari, Chrome) are gearing towards that day. I'll agree that for the "here and now" most users (myself included) feel that a browser is "broken" when it doesn't work with certain sites that I'd expect it to. I frequently change between IE and Firefox (but only ever open Safari and Opera for testing) to get the best results from certain websites.
The point they (Google, Opera, Apple) are trying to make is that the world *should* conform to the web standards and make things work the way the specifications dictate they should. The best way to get there is currently is following the XHTML strict standards and then move forward from there.
My client's sites are a little more varied than your results above, and it may be indicative of their target audiences. I have found roughly 75% IE (drilldown to roughly 80% IE7, 20% IE5/IE6), 20% Firefox and 5% "other". Marketing research studies have shown that, in general, that is the case around the globe. As I mentioned though, it really depends on your target audience. If we ran numbers like that internally at my day job, for example, we'd have 98% IE6, 1.999% IE7, and then two people using something other than that (because they have a mac). If we branch out to our corporate website, our numbers reflect more closely the above numbers (and have a much larger sample; ~300k users vs. 900).
So long story short, we can't be shortsighted as individuals and certainly not as a community and say that supporting Safari, Opera, Chrome, are not worth it because they will just disappear or because "most mac users have switched to Firefox". I'll venture a guess that because Chrome is a Google application it will do very well. Does that mean I'll use it? Probably not. I tend to use the tools that I feel comfortable with and those tools are primarily Microsoft. Does that mean I should ignore it? Defintely not.
That's my bit anyway.