SomeCreep - I wish it would happen - but I have a feeling with so many virtual hosts out there in the non-adult world using subdomains as their main tool and so many valid sites on subdomains, it's gonna be tough for google to do more than they already have
The linking together part is even tough as that requires them to use the whois info, and that kinda load on their servers doing the checks and mapping web links is probably beyond their automatic capability.
The only exceptions I can see are where it's something so drastic as the link-farms that were selling PR and flying way above the radar with 50 thousand domains linked together - us little guys that have a few hundred domains probably wont get a second look unless there is a really good reason - like dumping tens of thousands of subdomain pages into the SEs - those usually get spotted by someone and reported right away