Google buying Adobe is not going to happen. Google's specialization is all about using AI (suggest, spell check, translate, newsbot etc) and in making search blazing fast. Google's methods scaleout to millions of servers. So scaleout, using AI (and associated development tools), search, algorithms, statistical inference - google's hands are very dirty with technology, a very hands on engineering company.
Adobe has adobe, it has macromedia (very uncool if I was a googler). Google's mantra is "do no evil" - thats also a criteria too.
Does Adobe have an emerging technology that google absolutely must have - (in their time youtube, blogger, picasa etc.. were all such). ?
Google talks lisp, python, ajax - does Adobe talk that too?
The deal will need to be approved not on wall street, or in a board-room - but it will need to get the 'coolness' nod from the phds and the google math guys.