They will tie in record if the Spurs lose at Minny and Miami wins the last two (Bobcats and Magic)--both relatively plausible. Miami and SA split the regular season record. Miami has the better conference record, but I don't know if this is the tiebreaker for the finals because they are in different conferences of course. Given these two teams are the favorites (at least 50/50 to represent their conferences), this is important and IMO does not make the these last games meaningless.
The relevant tiebreaker seems to be better record against the other conference. Both teams have finished their interconference games -- San Antonio was 22-8 and Miami 18-12. So, the Spurs have clinched home court for the Finals (provided they get there) and have nothing left to play for. (Or, if you prefer, you can say that the Spurs have home court because they have the worse record in their own conference.) Source: http://www.nba.com/pacers/news/question_040405.html
Quite an odd tiebreaker and nearly as abitrary as if they based it on each teams own record conference. I could suppose you could argue it is better because it penalizes the team in the supposed weaker conference rather than rewarding it. Still, you would think they would do winning percentage versus playoff teams or some up with something different. But I assume the link is correct. Thanks for finding it.