An article from CNET describes the reactions of Red Hat, HP, Microsoft, and Sun to the claims by SCO that Former-AT&T IP was stolen and infused into Linux.

Each company reacted a bit differently:

• HP claims there are no grounds for the suit and that it is a dispute about IBM
• Red Hat claims there is no infringement
• Sun claims they have paid a large amount of money for their licenses a long time ago and thus Solaris is fine
• And Microsoft, as we know from yesterday, licensed the code in order to "support intellectual property rights" (in other words, to help SCO fund the fight against Linux).