The portable gaming landscape has come a long way in the past 5 years. I picked up my first portable gaming console in 2006, the Nintendo DS Lite, and it was alright. I enjoyed it in Airports mostly.
Now, 2010... Apple is making quite a major push into this space, with GameCenter, which, imho, will blow Nintendo and Sony out of the water. In addition their recent hire of Matt Cassamasima from IGN(Nintendo) to evangelize the platform to developers and customers (i think), shows that Apple is very serious about portable gaming, and i think they stand a good chance of taking the lion's share in the coming generation.
Sony's PSP, has essentially stalled in the market imo. Their mobile offerings (phones, PSPs, etc) are still too fragmented. I think E3 should bring a unified portable gaming platform from SONY.
Nintendo seems like a generation or 2 behind in terms of connectivity and delivery, primarily due to the lack of the back end infrastructure for such a service. And they seem most likely to be 'left behind' at this point IMHO (given the company's stance on these technologies and services). I Dont think they have the expertise in-house and should, at this point, acquire talent to become competitive in this space...if they are serious about it.
Discuss.