@sri429 While focus is the state most browsers leave on a clicked element (it didn't used to be all browsers, I remember), most graphics designers don't like seeing a focus ring on something that's been clicked. It's another reason people use outline: 0-- it's not because they were keyboarding and found it ugly, but they were mousing and found it ugly. So I use a very modified version of a little script @SteveFaulkner posted on the Paciello blog a while back to only let my focus styles appear if the event wasn't a mouse event.
It is possible that some touch devices run through a mouse event which could screw them up... I can't remember which but remember looking through some ginormous table Patrick Lauke made of all the events a touch device goes through and in which order, and I thought a few added some mouse events.