The openness of the PS3 is obviously more endorsed by Sony than I first thought:
I also particularly like how they've made sure you can use the PSP as a remote control:
But, most of all, you can install third party operating systems:
Install Other OS
Like for instance Yellow Dog Linux! I guess one will be able to use a USB TV Tuner and for instance Freevo as well.
I will however wait until others have tried using the PS3 for all these things, especially as a generic media center.