Yes, I have some IE9 issues fresh on my mind, even though it is superior to it's predecessors; it's still lacking in many areas. My issue was with a flaw in the IE9 JavaScript event methods; which of course I only found after chasing down 100 other leads. Some of the recommended fixes required special meta tags to deal with IE's "compatibility view"; which of course has to be the first meta tag declared and causes other issues once deployed.
In terms of what I was working on, it just meant the twitter button would not load reliably all the time in IE9. Kinda disappointing when it works in Firefox, Chrome, Opera, and Safari. At least it produces a link which accomplishes the same effect, I guess.
In turn I either have to release something that does not work as intended on IE9, or turn something that should have been fairly straight forward into something much more complicated.
Guardian, are you saying that conditional comments are being removed from IE10? I guess we can hope that we can treat it as a normal browser, but I'm not holding my breath... lol. IE will have to dump things such as "compatibility view" which tend to always infer that issues on a given site are because the site is coded improperly. In many cases with IE, it's the browser at fault.