Why Adobe and Microsoft Hit Delete on PDF Deal: "Adobe has its own monopolistic instincts: Last year it bought what was by far its biggest competitor in the graphics-software business, Macromedia. And it's been happy to exploit the demand for its free Adobe Reader to push unrelated software on users -- the Windows version normally comes with a Yahoo toolbar and Adobe's Photoshop album photo organizer.
Microsoft, meanwhile, has a history of taking standards developed by other companies, then writing software that somehow makes them work best, or only, on Microsoft operating systems. That conduct helped Microsoft lose many of its antitrust battles in the past decade; it's easy to see why the company wants to avoid a return to those days.
Still, from what we do know, it's hard not to wish that the bad old Microsoft would reemerge for this one occasion and tell Adobe to go pound sand."