Lukasz,
I do not believe that every Creo Parametric 3.0 commercial license (eg. PROE_FoundationAdv) will enable user to open CATIA files. I have never seen information that PTC is going to provide Creo Unite technology for free.
Currently, BETA testers can run Creo Parametric 3.0 Pre-release version using special license, which contains almost all modules. Therefore they are able to open CATIA models.
Martin Hanak