I'm not sure why a freely-available, free download can be blocked with the DMCA, but it looks like Microsoft want you to download SP2 only from their servers. As unofficial distribution is apparently now illegal, does that mean that we can't download once and share the file with friends on dialup by giving them a CD?
I'm not sure why a freely-available, free download can be blocked with the DMCA
Does not DMCA cover copyrighted material as well? Just because its free does not mean people can distribute it without copyright holder's permission - example are free content pages hosted by many members of this board.
As unofficial distribution is apparently now illegal
Almost always was...
does that mean that we can't download once and share the file with friends on dialup by giving them a CD?
Pretty much so...
This situation will be either legally fixed or people will continue to defy the law in a way that is not possible to police.
Leaving aside the marketing elements of microsoft not wanting to be seen to support 3rd party P2P (because to a lot of people P2P either means something good or something bad rather than it being an issue with gray areas).
Lets take a few recent viruses as an example - the virus claim to have a patch from microsoft as an email attachment, microsoft's response is that the only place they offer service packs and patches is their site.
If the idea of getting a fix from a 3rd party rather than the vendor becomes too firmly embedded in the minds of the public then it could affect their ability to say "we should be your primary channel for these things" and could leave them even more open to abuse.
... and competition - one thing no company wants is to lose direct access to customers that they have. Microsoft wants people to go to Microsoft.com, just like (I presume here) most content owners from this board.