In this project the acceptance tests are written either
before the story is started, or at the beginning of the
iteration. We had a full testing team that was doing
their best to figure out agile testing.
RE: GUI Testing
We were using Rational Robot and some custom built
tools. We didn't use them for acceptance testing, but
rather as a smoke test.
We are going through exactly the same problem in our
project! We've been trying to implement what you
proposed here as a solution to remedy the problem we
faced. It's good to hear the solutions are working out
for your team.
-BH
For GUI automation try the following:
WATIR
SW Explorer Automation
Selenium