a solid state hard drive.
a cloud system for playing/saving games
a more integrated online system from the start... trophies for ps1/2/3/4/psp/psn games all of which will be available on the psn for download.
faster blu-ray drive
built in DVR system with program guides/ unlimited recording space via the cloud save system.

Just a more powerful CPU and GPU...that's all it needs. Despite the ps3 having plenty enough power, it is always nice to have faster load times and better graphics. I don't think it will come until 2013 or 2014 though, which almost guarantees a processor that can split a single thread across multiple cores, possibly transportation. No, I am not kidding, if anybody here watches Science Channel, transportation is currently feasible to small degrees from one part to another part. This will lead to extremely fast computing since the data will have a much quicker path. Combine this with the splitting of the threads, computers will blow us away so much it isn't even funny.

lol you should probably start searching elsewhere...you know, just in case they don't put one in

It'll be ps3 BC. blu-ray disc will store up to maybe 1T of data maybe?

best idea ever. i can see it now ... playing lbp3 and eating some chicken

...5-D?

Maybe not.

maybe he meant it differently:

I remember back in the DC and PS2 launch time I always thought ok thats it graphics will reach a plateau for a while and I thought the improvment will be not as significant anymore.

Ofcourse I was quickly used to the better graphics and after one year or so I wasnt impressed anymore. 

Similar thing happened with HD consoles for a short time I thought damn how can they improve those graphics there isnt much more room left this time for sure. My friends also thought like that (and some still think improvment wont be that significant). I am talking about gen type improvments PS1 to PS2 to PS3. PC still hasnt reached a graphic level that makes HD consoles look like last gen even though I hope there will be such a game pretty soon. After watching hours of HD graphics I see more and more problems. I see a lot of room for improvment on all levels that I can easily imagine a similar jump like the jump between PS1 and PS2 or PS2 and PS3. 

I could name a million things which could be done better. More objects better animations better textures sharper textures. way better AA.

And changing the videogame worlds forever. For example if you make a Racing game on the ground could be thousends animated stones influencing the tires those stones could destroy accidently the windshield of the player behind you. Or grass every single plant could be animated and acting differently in the wind. Also grass always stands in games I have never seen that you were able to see some footprints in grass disappearing after a while. Also surfaces and objects are way too simple for my taste. They could be made differently for example completly out of voxels a wall (all objects) could be destroyed in millions of parts. Programmers would be able to transport their visions without losses in the videogames.  

I see more limitations in graphics then ever before. textures are always flat. Surfaces could be 3d also the lighing could be really dynamic and so on. The graphical improvments could be extreme between PS4 and PS3. If this gen goes longer then usual the improvment could be even bigger then the last improvments. And hopefully the industry will grow and developers can spend more money on game design. There is a picture which was handled as crysis 2 picture it was fake but games should look like that next gen or maybe the nextgen after nextgen (hopefully):

Mayhaps complete backwards compatibility?

It would be cool if it were to be it's own computer and then compete with Microsoft and Apple in the PC market. The PS4 can be upgraded as easily as a normal PC (CPU, GPU, RAM, HDD, MOBO).

Breakapart controller
1080p/60FPS standard in most games
Backwards compatibility with PS1-2-3