CSS3 media queries let me tailor layout to the width of a device. User-Agent inspection on the server side let me further tailor content specific to a device.
I have briefly read (but not yet thoroughly researched) that frameworks like jQuery Mobile or Sencha may (or do) offer touch gestures as a form of interaction.
Is there a standard to determine whether a device supports touch gestures or not? (With the follow through that I will then deliver touch or click controls to a user). Is this best done by the server, or are their client technologies offering this?
sencha and jquery mobile are still javascript frameworks.
check http://modernizr.github.com/Modernizr/touch.html for javascript detection of touch device.
And talking about server side detection, it can always be fooled. javascript detection is a better approach. But it is not fool proof either, we can only do so much with browser technology.