So are the cracks used to play your legally bought games without having the cd present in the drive. From a legal point of view you don't break any laws, you don't alter the revenues of the company and you don't damage the image of the company (because it all happens inside your own home)
The name crack just has a negative connotation to it.
On the other hand, if the game uses an online component then the company providing for the online experience can easily shut you out from that experience if you don't comply to their demands, these all fall under house rules or to put it in IT terms an EULA.
If one of these demands is, you can't use your own or third party software to alter the game mechanics or experience then you're rightfully exempt from the online component.

You don't break any laws, sure, but the problem is not only does the word "crack" elicit negative connotations, it does sometimes violate the Terms of Use and the EULA even if there isn't an online component.

I don't think they've ever been in anything close to grey, they've been fully dodgy from day one even when used for purposes which otherwise aren't dodgy

Sorry to break your bubble, but this has been possible for quite a while through the Blizzard store, only thing that's changed (I think) is that the Blizzard accounts and their functionality has been incorporated into battle.net.
And yeah, I too want them to add WC2bne to the list of supported keys. Either that, or put that one, Diablo1, and WC1 up here. (Yeah, not gonna happen as long as Vivendi's in charge.)

Really? I thought that it would only work with the games purchased digitally on Blizzard's store.

Other then the install at least starcraft and diablo no longer require the cd with the latest patch. You have to copy a couple video mpq files from your disc to the game folder but other then that after the install its cd free.
This does sound like a cool idea though, as my starcraft orginial disc has litterally 1000's of tiny scratches just from playing the thing so much.

That is great will have to do that 2 as like you my starcraft disc is a little worn out

Depends on where you live. Those of us living in the US risk violating the DMCA when we use cracks for games we own (and such violations can be prosecuted as a federal felony). The rest of you consider yourselves lucky your governments haven't yet gone completely batshit insane when it comes to IP protection laws.

Yeah, this is great. Was able to find my old D2 + LoD keys, but the discs had shattered a long time ago. Was able to download and get my Bhaal on!

I completely forgot about the DMCA, which is a piece of utter bullcrap.
So yeah, it would be an offence in the USA.
Also it's not exactly a matter of IP protection laws.
On a meta level it is even more disturbing.
In fact this law is a vehicle for a specific industry to alter consumer behaviour. This has absolutely no right to be in a law in the first place.
It would be the same as let's say the apple producing industry (the fruity kind) are a bunch of nitwits and see the decline in apple consumption. Instead of going for product differentiation or accepting that the times have changed and it's time to do something completely different, they then decide to bribe/lobby with the government. The government then decided it's not fair for the apple producing industry and come up with a law which forces every American to eat an apple a day.
Industry failure cannot be solved with industry specific laws.