I have just had it take my cup from the coffee table, all the way to the vending machine and get a drink dispensed !!
It is a bit hit and miss and I doubt it would manage to do it 2 times in a row without any problem, but it has managed at least once to work :-)
here is a video of it collecting a drink - http://youtu.be/IEv-7nvYL1M
I think my biggest problem now is the caster I am using at the back, when the robot has been turning and tries to go in a straight line again it tends to throw it off course. I have ordered an omnidirectional caster which I am hoping will resolve this problem but it is coming from the USA so may take a while to arrive.
Until I get this I don't think there is much more I can do.