@wyeyip:
On a device like the TouchPRO, you can slide you finger around the outside perimeter of the Action button - which zooms in/out. IMHO, I much prefer having the ZoomSlider handy as well.
ZoomSlider functionality is in three location - the first being in the STANDARD_SKIN.ZIP skin file, the second in the registry, and the third (for some builds) in the Opera .INI file(s). Opera 9.5 b16277 posted on the first page of this thread by Captain_Throwback supports the functionality.
Lastly, at least in Opera's case, the latest'n'greatest is not always the best to use if you are looking for plugin support, such as Flash, as some builds may not have plugin support enabled.
HTH,