Yes, the PS3 has Oblivion. However, you must remember that there is a major bug* that cannot be fixed on the X-Box and PS3 once you get the expansion.
*When they released the 1.2 patch Bethesda decided to change the value of "iShadowMapResolution," something that can be found in the Oblivion.ini file, to the new default value of 256. This caused a large number of nVidia card users -including x-box and PS3 users who use nVidia chipsets- to start experiencing random but consistent lockups of their machines; There are many reports of machines that had been stable for a year, but now easily lockup with the 1.2 patch. The lockup manifests itself as such: Randomly but consistently, WHEN ACTIVATING A DOOR, your entire screen will go black and you will hear looping sounds. Your machine is hard-locked at this point, no mouse or key combinations work, and your only option is to reset your PC.
This problem occurs for people that are using the latest nVidia drivers for XP as dictated by Bethesda in their README for the 1.2 patch.
For some unknown reason, third party hacked nVidia 8xxx series drivers appear to prevent machines from locking up. Non-Bethesda affiliated message board users have started telling other users to install these unsupported drivers on their machines to fix the issue. However, setting this value back to the original default value of 1024 (from when the game first shipped) allows the game to run stable under the last official drivers released by nVidia (93.71) for XP. Only Bethesda can explain why this value was changed to 256 with the 1.2 patch, and they have not done so at the time of this posting. Also, while I do not claim that setting this value to 1024 won't cause other anomalies with the 1.2 patch down the road, I do state that it will stop this specific type of lockup from occurring. There is no need to install unsupported drivers at this time.