Have to disagree, guys.
I have laid a dozen or more ceramic-tile floors on suspended wooden floors over the past 2-3 years in both kitchens and bathrooms, and not had any complaints (yet??). Only once did I have to lay a sub-floor, and that was because the boards were so warped it was impractical (read expensive in time and equipment hire) to sand down. I havn't used the Unibond product, but always use a proprietry brand. I never use pre-mixed adhesive - always get the powdered variety. For wooden floors, this is mixed with a (supplied) chemical solution rather than water, and this does not set hard.
Obviously, if there is too much variance in the surface of the wooden sub-floor, then you will get problems. As a rule of thumb, I allow a maximum of 5mm between the highs and the lows - any more than this then you have to use tons of expensive adhesive. Also very imprtant - ensure that there are no loose boards.
In any tiling job (floor or walls), I always use a separate grout - the adhesives that they say you can also use as grout tend to be very gritty, and you don't get such a smooth finish.
Hope this helps Nordic.
Del