As mentioned here, I have on occasion seen the site load with no font displayed.
This issue has only been observed since the infrastructure upgrade, and I have seen it 6 or 7 times now on two different computers, both running Chrome 35 (non-portable) on Windows 7 x64.
I have so far only ever seen the issue on the recent posts page (may happen elsewhere, may not, I haven't experienced it personally), and it occurs with a standard refresh (and possibly a forced refresh but can't be 100% sure).
It appears that the Google web font IS loading properly, as unchecking and rechecking the font-family entry in the browser's developer tools then makes the font show correctly without any further network access, it just seems to be that the font is not being rendered.
I'm still waiting to see if I can get it to happen while I already have the console open in case there are any errors, or other information, I can glean from the issue.
I'd wager unchecking and rechecking the font-family causes it to reload from cache but not network... but it's still reloading/re-rendering the font. If something as simple as that 'fixes' it, it sounds like we're somehow triggering a bug in Chrome which isn't that unusual (as the youngest browser, it's also the buggiest in random edge situations). Nothing in the page has really changed that could affect it. The CSS file is still doing a basic @import of the Arimo font on the first line.
Please post a comment in this thread if you can get it to occur with the console up or if you can determine any other commonalities to it happening.
Sometimes, the impossible can become possible, if you're awesome!
I had considered something like that.
Looking further into it I am starting to see a pattern that might indicate the source of the issue.
Looking at the request headers for the .woff files I see two different IP addresses being queried. Requests to 74.125.237.202 have always worked, while requests to 74.125.237.106 have always failed.
Based on the regularity of how much more I see 74.125.237.202 I am thinking that this IP is a primary, while 74.125.237.106 is a fallback (at least for themes.goolgeusercontent.com).
So this seems to indicate it is more of an issue with Google's server, or something on the network between me and that specific IP.
When I have a chance I will test this out in another browser and see if it is limited to Chrome, or I am just seeing it there because that is what I use 99% of the time for this site.