And, until google ports it to Safari, they can use Firefox.
Dictating which browser someone must use in order to use an open project smells terribly wrong. "You can take this road but only if you drive a Ford. Don't like Fords? Can't use one? No access." (might be a poor analogy but I'm pretty picky about my browsers and what I install on them)
It is deceitful and wrong to say sidewiki is not cross-browser -- as a terminology nazi you should know this. It ran on two browsers in the initial release!!!
To me, "cross-browser" means all major modern browsers, though often I'll even include Lynx in that. In the web-dev world, that's what it means.
Just because it doesn't run on your closed-source proprietary browser of choice, doesn't mean it is "dead in the water."
Sorry it seems like I'm nit-picking, but the only closed-source browser I can think of listed by others would be Opera (which is otherwise rather awesome and surely the preferred browser of some monks?). Web-kit is open-source, KHTML is open-source, even Chrome is open-source. But that aside, requiring a 3rd-party plugin and Registering with tehGoogles (do I get a star on my shoulder with that?), if this were the only way to access this, makes the internet-hippy in me look twice.
Where are the browser stats for perlmonks or cpan.org? Lets show up, we apparently require more data to determine if the costs (more work for OSX users), is worth the gain less work for Firefox/Explorer and soon Chrome users.
Why not some progressive enhancement? Those with certain browsers and tools can use the "better way" while still allowing access to all? Why block access to some?
Browserstats are always suspect. Look how often Opera has to masquerade its user-agent id as "Internet Explorer" to prevent getting borked by sites who do browser-sniffing (which have lately been puking on "Opera 10", as sniffers haven't been trained to read a two-digit browser version number and think it's "Opera 1").