I think it will be Boston vs the Lakers in the finals, and its a tossup as to which team wins.
I do not see Shaq inproving Cleveland at all, unless they can trade Z's expiring deal for a good small forward and some bench strength, e.g. Ilgauskas for Stephen Jackson and filler. But why would Nelson do that? Ilgauskas is a terrible, terrible fit for his offense. Z for Nocioni and the injured Francisco Garcia makes a little more sense, but not much.
Cleveland's other problem is the D. West may have limited or no utility until he gets his head straight. He was a key player for them last year.
To beat the Cavs, your big men simply have to beat Shaq down the floor. That is a task that is becoming easier and easier with each passing year.
The team I see really rising in the East is Chicago. They are learning to play together, plus they have Deng back. IMHO they won't miss Gordon at all. I wouldn't be surprised to see a Boston Chicago ECF.
In the West, the addition of RJ is too little, too late for the Spurs. They still don't have the horses to challenge the Lakers, who will be scary good if Artest works out.