The statement will confirm the worst fears of the open source community.
What fears? If MS was going to attack someone for infringing on their patents they would have done it already or at least they wouldn't have signed on with Novell without some pretty big alternative motives. That's the nice thing about OSS, the code is out there for anyone to look at so MS has had all of the time in the world to go through an audit.
And the worst case scenario for most people is that if something is found to be infringing it just needs to be rewritten. The obvious candidates for this are Samba and the Linux kernel support for NTFS, smbfs and cifs. And IIRC CIFS was submitted to the IETF for standardization so they'd probably have a hard time attacking that one.
And from the part that kamper quoted, Ballmer hasn't made any claims about anything other than he feels that Linux customers don't know if they infringe and with the new deal only Novell customers can be confident that nothing bad will happen even if they do infringe. Essentially Novell has just bought insurance for their customers just in case MS does hit blackjack. And it probably gives Novell the clear to pursue some things that other developers have avoided because of potential violations, but I don't know enough to speculate accurately.
...Along with basically every buisness, consumer PC and government installation in the world.
And that statement should cause a big light to go off in everyone's heads about how important open standards really are.