Google has announced to support the current version of 4 popular browsers and the previous version, and we've adopted that as our policy as well. I guess Trello has the luxury to be able to not support IE8, you lucky bastards ;)
In the end I guess the target market probably won't be the kind of person who has IE8 installed while unable to upgrade, the only downside I could see is if you as a consumer wanted to use it with clients.
I'd also say Google's 'decision' is totally arbitrary and only meaningful in relation to IE, more specifically support for IE7, don't copy them. What if MS start releasing versions like firefox are now? FF also got some flack from corporate clients who can't keep with the schedule. If a massive corporate with XP machines who are unable to go past IE8 suddenly pops up on Google's radar I wouldn't be surprised if that policy suddenly disappears when IE10 comes out.
Just kidding.
Imagine a traffic chart. The x-axis is time. Trello will last for 20 years, so imagine it going from 2011 to 2031.
The y-axis is usage. The numbers climb up and to the right. We think we can get to 100 million. So imagine either a linear curve or geometric growth or whatever you want, climbing from zero to 100,000,000.
Now think of the area under that curve.
What percentage of it is using IE 8?
Is it worth spending much money on them? Is it worth slowing down to build something for a small group of users that will be gone anyway, and which are only a tiny percentage of the overall usage of Trello over 20 years?
I've started using Trello for personal projects and a little at work, and finding this kind of stuff is awesome. Knowing I won't have to fiddle with zooming in and out on my iPad/iPhone makes Trello a service I would love to pay for.
Quick question about how you are handling security for your API. Are you using a 2-leg OAuth setup for your web requests? How do you handle the security of having the "secret" in the code?