I have an idea I hope they implement into Black and White, or another future game.
Portable PC's. Pretty much the exact same thing as a PC, but you can take it with you instead of having to visit a Pokémon Center to use one.
Now, you may be worried about something; Hey, this would make training Pokémon much easier. And if you could just use this anywhere, wouldn't it break the game?
The answer is no. While you COULD use the PC to switch out party members at almost any point in the game, there are some restrictions. Here's where I introduce another idea; PokéNet. This is basically the internet in the Pokémon world, where you can search for tips and tricks, check out trainer's websites, manage your bank account, and look at some neat-o videos. Each of these has a specific function; Searching the PokéNet would act as the Teachy TV, trainer's sites would be the Call function of the PokéGear (possibly replacing that), the bank would be holding money from battles, and the videos... I haven't really figured out what those would do. Maybe to record battles.
BUT! The most important part of this would be restrictions. While all of these are unlocked once you get the PPC, there are certain places where you cannot use it. Examples being in a cave, during the Elite 4, during a battle, and when using Surf or Dive (if that is brought back). All of the normal PC functions will still be on it; Storing Pokémon, asking the Professor to check your PokéDex, and viewing photos.
If there's anything else you think should be added, just tell me your ideas. I might add them to this core idea.

Yes, a laptop item would be very useful (along with the restrictions you pointed out).

Maybe if you're on a really big route your internet cuts off part-way through it. Like you have bars on it (Like the WFC bars you see when trading/battling on Wi-Fi) and they deplete the further you are from a town.

Yea sorta like nin said. Like you can't use it in caves or anything like that because the reception is bad~! =w=

The only flaw in this that I can possibly see is that Pokemon can be healed through the PC (as all Pokemon are when they are inserted into a box). If you're walking a route and get poisoned or paralyzed, what's the point of having antidotes or paralyze heals when most of the time you'll be able to just swap them through the PC?

The only other change I would make to this then is that you can't heal through this PC on the road. Sure, you can have a party of 12 healthy Pokemon upon leaving, but on harder routes where it should be more challenging, you shouldn't be able to just swap, heal, swap back, and keep moving.

Takes the challenge element out otherwise.

Its an interesting idea. As early as gen three they were talking about expanding the Pokémon you can have on you and the moves they can learn, and I am very much hoping Gen-5 will show some of that (seriously, we need a competitive battling refresh).

Sacred Ash + Full Restore = PPC?

Well maybe you can only use it at areas with wi-fi.

I think a laptop would be a great idea, as long as they make it so Pokémon in the PC aren't all set to full health, or team re-organizing cannot be done with it. The reception idea sounds pretty cool, as well. I think the ability to use the phone in a cave in HgSs (I don't think it was possible in GS.) was a pretty bad idea.

I like the idea of the laptop, and the reception does seem like a nice counterbalance, but the problem of perfect healing whenever a Pokemon is sent through the system would break the game challenge. Either they would use JustJack's idea, or perhaps they could do something similar to this:

My idea is that transfering Pokemon would only be possible in areas that have full reception strength. You're sending the genetic code of an entire living creature across the internet, so you'd need the very strongest connection you could get. These would occur often enough that the PPC wouldn't be entirely pointless, but they would also be infrequent enough to retain the challenge.

Maybe the PPC and the PC Boxes are different, like you can't access PPC boxes from the PC and vice-versa.
That way they could justify PPC and PC boxes not healing or something, however I'd think it'd be great for something at the end of the main game, not towards the beginning(at least the PC part of it), cause if it were open in the opening of the game, then it'd make it really easy.

If it were open at the end only, then it'd be perfect for EV training and such, which would be awesome.

It's a cool idea.

That would be pretty cool.
I will love every thing brought in B/W!