To preempt a few questions that are bound to pop up:<p>What about jQTouch? While jQTouch is a great framework and we're proud to have it as part of the jQuery community - we really wanted a mobile framework to exist that would truly support all the mobile platforms out there. We chatted with the jQTouch team and there wasn't really any interest on their end to head in that direction. It's obviously going to be a ton of work - but that's something that the jQuery project is very interested in tackling.<p>Is this a response to Sencha Touch? We've actually been working on jQuery mobile for a while now - long before Sencha Touch was released/announced. We're not particularly concerned with Sencha Touch mostly for the same reason that we're building an alternative to jQTouch: We want to support more platforms and do it in a completely seamless way.<p>What data did you use to choose the browsers that you did? We've been talking with a number of mobile analytics firms and large corporations, gathering data, and will be releasing a bunch of the reliable numbers that we've collected on the jQuery mobile blog. Right now we're confident in the browsers and versions that we've chosen - although that'll likely change over the next couple months as the market shifts.