User experience design in the context of Agile development seems, for some reason, to remain a hot topic. There is a perception that design and agility are somehow in conflict, which seems odd to me – I’ve always though of design as a naturally Agile process (if only due to it’s inherently iterative nature – all design solutions are always open to improvement).
I tend to think of design as something that begins before development in order to, first of all, validate the business hypothesis, then provide context and frame the problems being addressed during an Agile iteration cycle. Business and customer feedback from deployment of the cycle (sprint, whatever) subsequently helps inform future design efforts.
Even when the overall strategy is as banal as to simply throw shit at the wall and see what sticks, I have found that costs can always be mitigated to a signficant degree by having a little more customer insight and knowing, to extend the metaphor, which bits of wall are likely to be sticky.
Austin Govella has six useful points to bear in mind, touching the importance of on modeling, collaboration, and communicating effectively, amongst other things: http://www.thinkingandmaking.com/view/agile-ux-six