So there is a magic development fairy who waves their wand and changes the amount of work required to make the exact same game based on the platform it is delivered to?

Portable games tend to cost less than console games because the scope of the projects tend to be dramatically smaller, and the quality of their graphics tend to be much worse than current generation consoles. If the scope of the project is similar, and the quality of the graphics remain similar, the development costs of two projects will be similar; regardless of whether one project is on the NGP and the other is on the PS3.

Nothing I say is "guesswork", and most of it is well known facts and/or common sense.  If you really do want to understand more about the project side of the videogame business you can start reading articles here: http://www.gamasutra.com/features/production/

I for one think it's going to be the cheapest.  Having innards like an Ipad means that development costs might be as low the platform.  All those dirt cheap mobile games will be on PSN and NGP.

You may be correct, though I don't think it is a simple as that.  I do think it was a wise move by Sony to adopt an evolution of a pretty ubiquitous architecture.  However, NGP games will feel and play differently (thankfully) due to having actual buttons and other gamer niceties.  There will be more to porting than just the code... or those ports will fail.

It's also worth pointing out (though) that 3DS is based off of the same CPU family, so (from a code perspective) anything that CAN run on 3DS from the NGP library will not take too much to port either (and vice versa).  YMMV.

It's not that simple but almost so. 

People who are developing for mobile first wont have to change anything at all to get their game on the NGP.  It doesn't have to use those butttons because they are there and the NGP does have multiple multitouch panels. This of course is only if Sony allows such practices as they do sometimes require extras for ports from other platforms to be on their platform but if that isn't the case given the price of labor those ports can't fail.  Minis seems to only make that seem more feasible.

It may be worth pointing out but it doesn't do much to help the 3ds because of the massive difference in power between the 3DS versus the NGP and iOs devices and smartphones. It will end up like the Wii.  It's possible for the Wii to do many this gen games but as it's just not seen as sufficient return on investment in trying I think It will be shunned.  That is of course mostly with western devs and the multiplatform way they have developed their workflow and how they wont view dumbing it down as worth the time instead of investing in current and onward technology. 

This is all of course just me stretching out current attitudes of developers into the future but it's been pretty consistent for a while now.

that is why sony is dowplaying the "as powerfull as PS3"

It is much more complex than that to estimate costs. Better development tools alone could drop budget by less than half. For example, making a background graphics with bad program could take 3-4 times as much time as with good program and you still end up with identical graphics. If NGP has better dev tools than PS3, that alone could drop budgets a lot.

Same game can be made by good team with 10 million while an average team could spend 50 million and still end up with worse game. Heck, Crysis is still considered having best graphics so far and it costed 22 million (still, it was considered a huge budget for a PC game), much less than a lot of games in HD. 

Sony likes big projects with big costs if i were you i would just get used to it.

I agree on the power differences, but I don't see that it makes much difference to most iOS games as they are relatively simple, and would port to 3DS without issue.  Obviously, the phone games with NGP levels of graphics won't make it without cutting, but (honestly) can't we agree that the VAST majority of these titles could run on a 3DS?

I can't necessarily agree with vast majority as they have problems getting these simple games to android phones that smoke the 3DS as far as cpu and ram goes. So even those simple games might require cutting or major reworking which goes against the western multiplatform workflow and development.  It's definitely possible(as we have seen with japanese devs like capcom and versions of their mt framework), but I wouldn't go as far as to it's at all plausible to western devs who are the ones making iOS shine.  As some Japanese devs go on to find larger successess on the mobiles I can see that support eroding too.