There are good reasons to believe that usability and Agile development methods can work together and improve user experience quality:

Agile offers many opportunities for overcoming problems with traditional development methods that have long impeded usability.

Approaching Agile narrowly, as a programming methodology rather than a system development methodology, threatens to destroy the last decade’s progress in integrating usability and development. But, as outlined above, there are ways around each of these threats. So long as teams recognize the threats as explicit issues, they need not harm product quality.

Finally, we know from our research that many companies have made things work swimmingly — once they adapted the Agile methodology to suit quality-focused system development.
For user experience practitioners who support Agile teams, the main change is in mindset. Having good, general user experience knowledge will help you understand how to change traditional design and evaluation methods to meet your Agile team’s different focus. Ultimately, however, you must both believe in yourself and embrace Agile development concepts if you want to succeed.

If you’re prepared to change your practices and take on the responsibility, there are great opportunities to improve your effectiveness and your impact on the teams you support.

Usability definitely seems to be one of those expanding possibilities.  Having resolved the most serious glitches in their software engineering processes, teams seem to have more energy to spend with their users.  Innovators in the Agile community are focusing on usability

Kathy Sierra recently envisioned software that’s not just usable, but SO usable it’s transparent.  Its users becomes immersed in the task at hand, as the software empowers them to handle the challenges of their work, without intrusive distractions, workarounds and constraints.  She describes this user experience as “flow”, a term coined by psychologist Mihaly Csikszentmihalyi to describe complete and energized focus in an activity, with a high level of enjoyment and fulfillment.

Alistair Cockburn, in his recently revised “Agile Software Development: The Cooperative Game” specifically commented on the difficulties some are encountering with usability:
In some organizations, would-be agile programmers drive the timeline and insist that the UX design be done incrementally in two-week iterations, simultaneously with programming. The UX [user experience] designers complain that there is insufficient time to research their users, create a design, and program it within the two-week window.

Cockburn’s recommendation: adaptation. Teams must address these realities: all stakeholders must collaborate to examine this tension between overall consistency and incremental development.  In the end, it’s the familiar prescription for process problems: experiment, reflect and adjust.

More information: http://headrush.typepad.com/creating_passionate_users/2007/01/what_comes_afte.html

Robert Barlow-Busch argues that traditional usability testing is too slow to properly support an iterative approach to product design. He presents the “design checkpoint” as a complementary activity: an informal exercise in which 1 designer meets with 1 user for 1 hour every 1 or 2 weeks.

httpv://www.youtube.com/watch?v=WgxKyuglbT8

From the “7 Minute Soapbox on User Experience” in Waterloo, Ontario on June 14/07, in which speakers had exactly 7 minutes to present their ideas.