Previously this was only in the US (to my knowledge).
I read about it here:
HP To Refund Pre 3, TouchPad Customers | ITProPortal.com
Applies to Touchpad 16/32/64 GB (wifi only) and Pre 3, but only if activated on or before 23/8.
Hopefully you've kept your invoice- you need to submit a scan of it. I don't have mine so I used a screengrab of the shipping confirmation. I hope that works.
My Touchpad was eligible for the rebate but not my Pre3, since I activated it after 23/8 Oh well, I consider myself very lucky to have one.