I agree no one would use it doesn't stop that being what they were talking about...  Think about it in context the slide is talking about what you can do by linking the Vita and a PS3, Notice the rest of the slide mentions spacifiaclly "Use the Unique features of PS VITA as a control device" and the the presentation as a whole is focused on networking the dev one is seperate.

There is also that they are currently caping the games at 4GB meaning devs can't use the same assets unless you are talking PSN titles...

And then there is 

"Eurogamer: That was my next question – what are you going to do to stop people simply porting games across to it? If it's that powerful that you could bring a PS3 game across quite easily...

Andrew House: To be honest, the publishers that I've spoken to have generally indicated that they don't think that that's satisfactory for the consumer. To try and ask the consumer just to re-purchase an existing console experience – I don't think we or they feel that is really going to be the correct strategy."

Also your avatar is creepy as hell

Yeah i think the OP has got the meaning of this slide wrong, It just means Vita could contribute to a PS3 game without PS3 having to use additional resources communicating with it. Nothing to do with the Vita having the same processing power as PS3,

Sony and developers have said its easy to develop for though and porting games is easy to do.

i get it but that is just a feature,it will be hard for people to do that with the cost and the knwoledge needed by sonsumers

another reason is that SONY wants people to make handheld unique experiences after PSP as that will promote VITA on its own games.

though this thing as game portability has been talked about since day one.it will depend on the dev

Dude, you should totally be expecting to. At best, some publishers will offer a voucher to download the Vita version for free or in most cases at a big discount with the PS3 version.

No they dont.  It's called the Phyre Engine. You can develop one game for PSP, PS3, PSV and PC all running the same code.  This is great for japanese devs and smaller indie devs.  Probably a part of the reason we already see many PS3/PSV games coming from japanese devs.

thats great news

The code that the Vita and PS3 would be running would still be different just Sony did most of the work them selves, it's not like you could use the old version of the engine. But devs could use the version Sony ported over. The Vita uses very different hardware, new APIs (aparently some of the best console APIs arround rivaling those MS created) and new dev tools that have recived much praise from devs as it is much better designed than the PS3 tools, the systems are nothing alike and that is a good thing. 

But then a year later Vita-PS3 intercation will become totally obsolete, when the PS4 comes out. So even if the conclusion of the OP is correct (which I think it isn't, not exactly), this whole functionality is actually worthless, since at that point developers will stop making games for the PS3, with PS3 owners moving up to the PS4.

[added] One could argue that Vita will be PS4 compatible as well, but given that PS4 will be so much more powerful/different than PS3, it will just be PSP-PS3 interaction all over again[/added]