Nicofan hinted on this topic earlier, how the Olympics are killing the summer hard courts schedule.  I agree in a similar way but specifically how it is going to effect the results at the US Open.  The Olympics are held two weeks before the US Open starts.  Theoretically, the players should be well-rested before the Open.  However, there are problems with recovery after  a long travel between time zones (Beijing and NY), and just playing too many matches.  

To win gold, they have to win 5 doubles matches or six singles matches without losing any. Depending on how well the players do at the Olympics, the results at the US Open are going to be inversely effected. 

Back in 2004, Federer lost to Berdych in the second round in Athens, and  then lost early in the doubles that same day.  I believe his losing early at the Olympics helped him win the US Open.  Hewitt did not play Athens that year, and made the finals of the US Open.  Agassi did not play it either, and then made the quarters of the Open, only to lose to Federer in five.  Roddick lost in the quarters of the Olympics and of the US Open.  Massu won the singles gold but lost I believe in the third round of the Open, and he and Gonzalez won the doubles gold and then lost in the semis of the Open. 

Since Federer, Nadal, and Djokovic are playing the singles and doubles events, they are going to be spent mentally and physically if they do very well there.   They have good partners in Wawrinka, Robredo, and Zimonjic, respectively.  I believe Federer can go very far in the doubles, and I hope he wins gold in that event at least. The doubles are going to be the most unpredictable because most of the players are lowly ranked, and their abilities and rankings are not going to reflect each other.  Federer, Nadal, and Djokovic may face each other in the early rounds of the doubles.

The singles are brutal because the players in the event are mostly in the top 80 in the world; unlike in other years when players outside of the top 250 were also in the main draw, and made the event less competitive. The singles are going to be competitive from the word go. 

As great as the top three are, I do not believe they are super-human.  I just do not believe any one  of them can win the singles, doubles gold, and  the US Open singles. Any one of them can win one of these three events, possibly two of them, but not all three. 

I find this Olympic year an exciting one.  I envy all athletes who get a chance to participate and represent their country.  I hope any of the big three can do well because they are from countries who do not usually win gold at the summer games.  They are going to be hungry.