So first we have to find out, that what Reggie was meaning by "WiiConnect24 users", did he mean everyone who has Wii online, or people WiiConnect on that certain moment, or a special online feature that WiiConnect uses.

Demo channel might be possible, even without HDD support, Super Mario Sunshine would easilly fit to the flash, so why wouldn't a one level demo?
There has been rumors about the VoIp, so it could be possible.
NeoGeo on VC.
Online stuff for Metroid Prime 3.
First WiiWare game.
Of course, they could have something else in mind than what we can think of, Nintendo is good at surprising people.

bdbdbd, what are you talking about? WiiConnect24 means ANY Wii that is online, whether it is on the standby connection or not, as every Wii connects to the internet when turned on, so that is irrelevant.

VoIP? Er, no... where's the microphone?

And WiiWare software... they've already said 2008.

I think it would be something like a free VC download... or maybe the possibility to customize the wii's menu... like backgrounds... differente colours... that would be sweet...

As I read that in context, Keighley was talking about channels.  It will not be the "check mii out" channel, because then his statements make no sense, having already spoiled the surprise.  He knew Metroid was going to be out in August, so I doubt it was the Metroid channel.  Wiiware is something already on the shop channel.  So I'm thinking there's going to be some new channel.  I also don't see anything that suggests it is for the hardcore.

My guess?

No clue.  It's going to be something we haven't thought of.  Maybe they've got their own second life type thing (using Miis of course), and are being secretive about it because PS3 has already bragged about theirs.  "Mii Life" or something like that.

@Kelestar: If that's the interview, what jman posted, where the surprise has been said, Reginald doen't mention WiiConnect. Though, I have to admit, that i thought that Reggie mentioned the WiiConnect.

WiiConnect doesn't mean any Wii online (to be more specific, online Wii). The WiiConnect24 can be turned off, when your Wii can use other online features, but not the ones that WiiConnect24 offers. I think you got the point.
What i should have said is, that did he mean Wiis with WiiConnect on or Wiis with WiiConnect off. But now it's clear, that it's just a surprise and it somehow relates to Wiis online.
Some people seem to see WiiConnect24 as Wiis online and some people as the WiiConnect24 service.

Ok. VoIP, it's possible, they can release the mic or just use, for example the DS, or add BT headset support.
Has it been announced that WiiWare titles start 2008 or 3rd party titles start by then? There's a possibility that Nintendo could release their own WiiWare title. Or atleast i see one.

If I didn't say this before, there is a Nintendo event Sept. 5th. You do the math.

Why are there so many people who think Metroid Prime 3 will gain an online mode? Ridiculous.

I'm hoping for Brawl info.

There can be no Demo Channel without HD support. Unfortunately...

I think its the second half to this:

http://vgchartz.com/forum/thread.php?id=6433

In that thread we learn that Neo Geo games are coming to VC and we know Wiiware isnt to far off. But the largest NeoGeo game is 91 megs, and how in the world is Wiiware going to work with that limited storage space?

Answer is Septembers surprise. Firmware update to allow games to save/download/run from SD cards that we all are already using on our Wiis. They come in sizes up to 8GB and will ease us quite quickly into a new area where we can have good sized Wiiware games and support for NeoGeo and possibly Saturn (You know you want it) games without the need for an HD.

Guardian Heroes and Baku Baku animal on VC. Make it happen Nintendo.