The reason he didn't go to Dallas was because the Mavs wouldn't give up Nowitzki, so they wouldn't have teamed up.
The Heat gave up two good young players (Odom and Butler, plus veteran Brian Grant) to get Shaq who is getting old so it will take time to see if it was worth it. I think the Heat will now be among the top in the East (with Detroit & Indiana) but they lack depth since Dwayne Wade and Eddie Jones are the only recognised players they have to support Shaq.
The Lakers will most likely find out 2moro whether or not they will also lose Kobe Bryant who is deciding between them and the Clippers.
Its been a great offseason so far with guys like McGrady, S.Francis, S.Nash, Stackhouse, Q.Richardson and Boozer changing teams.