As hard as it is to say as a non-American, I can't help but feel like the Olympic trials so far in the other nations have been a support act for the main headliner... and in true rock star style, they are making us wait.
Here is a breakdown of where I see the US standing in each event, and how their stock has risen
/taken a fall 
or stayed the same = since Shanghai. First off, we take a look at the Freestyle events.50m Free
Men
Nathan Adrian remains USA's best bet for a medal in this event and outside of Cesar Cielo's 21.38 from the Maria Lenk Trophy, won't have seen anything too concerning so far this year. Fred Bousquet won't be there which is also a plus, but Bruno Fratus' emergence just about cancels that out. Behind Adrian they have comeback kid Anthony Ervin, established guys such as Garrett Weber Gale, Jason Lezak and Cullen Jones, as well as a group of young sprinters who they will look to make a step forward (particularly Josh Schneider and Jimmy Feigen).Women = No real change. Jessica Hardy,who finished 8th in Shanghai, was the top ranked American in 2011. A spot in the final with an extremely slim medal chance still appears to be on the cards at this point. The challenge to break into the upper echelons of the event has become harder with Fran Halsall and Ranomi Kromowidjojo joining Therese Alshammer in the 24.1s this year. The reason for the = sign and not the dreaded downward arrow is simple... Dara Torres. Until we see what shape Torres is in, the jury remains tantalisingly out.
100m Free
Men
The US men have been well and truly 'Magnussened'. Before Shanghai, Nathan Adrian was one of the favourites for gold, but is currently barely clinging to his place in the medal discussion. Australian's Magnussen and Roberts as well as Cesar Cielo, Brent Hayden and even Yannick Agnel all have the edge at this point in time. Realistically, Adrian needs to show up with a sub-48 second swim in Omaha to get back into the frame.Women
Missy Franklin is the unknown quantity in the 100m Free right now for the US. She swam an impressive 53.63 last summer, but has since seen Ranomi Kromowidjojo (52.75) and Sarah Sjostrom (53.05) move well clear in the rankings. It remains to be seen what Franklin and/or Natalie Coughlin et al can do, but the rest of the world, particularly Europe, has taken big strides forward during and since Shanghai.200m Free
Men = Tough event to grade. On the plus side for the US, we haven't seen any further progression from either Sun Yang or Park Tae-Hwan so far in 2012. However, Yannick Agnel's 1:44.42 from French Trials represents the biggest threat to US dominance since 2009. Agnel's time was 0.02 seconds quicker than Ryan Lochte's winning time from Shanghai, and while Lochte and Phelps are still favourites in the event, Agnel has a great shot at playing spoiler. We're also waiting to see what sort of form Paul Biedermann is in at German trials next week.
Women = Another tough grade to give. On the one hand, Camille Muffat's textile best time of 1:54.87, closely followed by Sarah Sjostrom's 1:55.23 have moved the event forward this year. However, neither time seems out of reach of Missy Franklin (1:55.06 last year) or even Allison Schmitt (1:55.83 untapered in January). Federica Pellegrini is still to show her strongest hand in 2012 and can't be discounted.
400m Free
Men
This may raise some eyebrows given that the US have been relatively weak in this event in recent years, but the door has been left ajar by Yannick Agnel's decision not to compete the 400m Free. Only Sun Yang has been quicker than Peter Vanderkaay's time from the Shanghai final this year, and if Vanderkaay improves in his second year in Florida he could pose an even greater challenge to Sun Yang, Park Tae-Hwan and Paul Biedermann for a medal. The US will also look to Matt McLean, Charlie Houchin or Michael Klueh to get into the reckoning for a top 8 spot in London.Women
The 400m Free has really kicked into gear so far this year. Camille Muffat set a new textile best time of 4:01.13, Rebecca Adlington continues to improve her textile best and is now down to 4:02.35 and Kylie Palmer has also lowered her best to 4:03.40. Added to that group, we are still yet to see a 100% Federica Pellegrini or Lotte Friis this year. The American women have depth, but they need to improve considerably to challenge for a medal. Allison Schmitt's 4:05.90 and Katie Hoff's 4:07.00 untapered swims are good signs, but still not in the same league as the women listed above. It may take a swim of 4:04 or 4:05 to have a chance of making the final in London.800m Free
Women
There is better news for the US women in the 800m Free. Although Rebecca Adlington is faster than she was last year and Lotte Friis is still expected to be her main competition, the 800 Free hasn't seen the level of improvement that the 400m Free has. Chloe Sutton has been 8:26 already this year and Kate Ziegler's bronze medal time(8:23.36) from Shanghai has only been bettered by Adlington (8:18.54) and China's Xin Xin (8:22.76) this year. At to the mix some young Americans (Gillian Ryan, Katie Ledecky) who could take big strides this year and the Americans medal prospects still seem strong in this event.1500m Free
Men = The US qualified two men for the 1500m final in Shanghai, but neither Chad La Tourette (5th, 14:52.36) or Peter Vanderkaay (6th, 15:00.47) could get close to the medal podium. This year has seen Park Tae Hwan swim 14:47, the emergence of Britain's Daniel Fogg (14:55) and China's Hao Yun (14:58), and the return to form of David Davies (15:00). On the plus side for the US, they have good depth in this event with several men knocking on the 15 minute barrier last year (Andrew Gemmell, Sean Ryan, Arthur Frayler, Evan Pinion, Michael Klueh, Mike McBroom, Ryan Feeley) who could be primed for a breakthrough this year.
