So what do you guys think?  I was just reading about the new PSP-GO & how it doesn't support the UMD cartridges, it's online only.  On the downside, you can't get the cheap prices from used/marked-down UMB disks that one can normally find.  However, on the upside, if a game is discontinued, you don't see these extreme $70 prices for old or used versions of the old games.
 
I've basically found that old games on the DS (perhaps also the PSP) are extremely high priced, compared to old games on Consoles or PCs.  So it might be favorable to have the online service, but it eliminates the used market & having a touchy/feely product.  I'm sort of at a disadvantage here though since I bought a DS lite, not the wireless one.
 
I was surprised to see the PSPGo toss out the UMD feature, so it leads me to believe they only want new customers to use it, rather than allowing it to work with the old UMB system & online at the same time.

I personally feel like the whole Sony booting the UMD has something to do with how you can (or perhaps more accurately) actually carry around a brace of UMDs.  With the DS, the cartridges are so small that I can carry around about ten games and pop them in and out of my DS with relative ease.  It's pretty goddamn hard to drag more than one UMD around.  This is a problem when your focus is to make a portable system.  Hence, I believe that's why this PSP is called the PSPgo because you can actually GO somewhere with it.

Nintendo's got a pretty decent thing going with it's mini-carts, and I have to believe they won't fully convert to DL-able games any time soon, but it made a lot of sense for the PSP to begin marketing itself as a purely DLC system.

I agree with most of the points here - yes the companies are trying to mimise the market for used-games at retail. I think a lot of these moves are motivated by Nintendo and Sony trying to compete with the ipod / iphone (not that it's anywhere as near being genuine competition for pure gaming as everyone seems to think it is). 
 
Yeah, DS carts are a doddle to carry. The main issue with carrying a batch of UMDs around is that they RATTLE like you wouldn't beleive. 
 
Sony does seem to be trying to figure out their pricing in all fairness, I've noticed that Riviera (an old rpg port) which hit PSN for about £23 in the UK last month, has now been dropped in price to £14 after the big October revamp. They've also started publishing the DL versions of new releases at £23 rather than the full whack £30 they originally experimented with (though some third parties are still in at the full 30 notes). 
 
Going forwards we'll just have to wait and see how it pans out I suppose. It is nice to be able to just think "oh, I'll play a bit of that", and it just be there though - it is trying to be the ipod of gaming, but is 16Gb enough memory? 
 
As for the DSi downloads, well I can't really comment - it's been MONTHs and they're still yet to post anything thats a full game (that isn't a port of an iphone app). Where is all the SNES emulation? I'd take their arm off for a dl copy of super mario world to play on it. Come on Ninty, sort it out.

My hope is that going into downloadable games in a big way will allow companies to be more flexible with their pricing on stuff.  I seem to remember at GDC or some other show earlier this year, someone from Valve was talking about how they'd been kind of experimenting with special sales and promotions on Steam to boost sales, and it sounds like it's been really successful.  Hopefully others will start to take cues from this.  In fact, just this week NIS put a bunch of its downloadable PSP titles on sale for half off.  If that kind of thing really takes off, the loss of the used market might not be quite so bad.

I have over 20 games on umd, I will NOT be getting a Go. 
It's also way too expensive.

" @Lind_L_Taylor: It really depends on what game you are talking about. Most of the popular old stuff on the systems can be found relatively cheaply, but cult hits (Etrian Odyssey for example) do get their prices jacked up.   Also, the Ds LIte is wireless. It just can't download DSi games. "

" @Lind_L_Taylor: I don't know about all of that. Part of the reason why the games on PSPGO are so expensive right now is because Sony is trying to avoid cannibalizing the UMD market. If they make everything cheaper on the GO, then more people will stop buying games in retail stores. This is what the companies in Europe and Australia that decided not to stock PSPGOs are worried about.  "