I think it's worth pointing out the gap in perception between many in the US and the rest of the world. US politicians are incredibly skilled in presenting America to the American people (as an international force for good), but the reality of the actions on the ground are often very different. Sometimes the actions are deliberate, sometimes they're unfortunate interpretations of genuinely helpful behaviour.
In the UK at the moment, there really seems to be a growing feeling of having been taken down a dark path by the Bush government. Namely that Blair's ego was massaged by the neocons, and that took us into conflicts of limited positive value, and great losses. Also that we've ended up being complicit in the torture of prisoners. That those directing US operations in Afganistan and Iraq (at government level) never actually paid any interest to the UK point of view, and just used us to give a veil of legitimacy to their actions (i.e. we have coalition, we're not doing this alone).
I'm not claiming that any of the above is fact, just that this is the perception. For that reason, the idea that the Obama presidency is treating the UK badly must be put into perceptive. Having said that, as highfigh pointed out "we can't afford to offend anyone and he should have thought of that" - given that there's really little to gain from a perceived snub, yes, perhaps someone in Obama's administration should have advised on avoiding possible insult.
As Davemcc noted "Bush pushed a lot of friendly nations into an anti-US posture". The US is a massively powerful country, with incredible capacity for good. The problem is that, rather than being respected by your enemies and loved by your friends, the actions taken by US governments often result in you being hated by your enemies and feared by your friends. Sometimes that power is the problem - friendly nations know the US has the strength to do what it wants, even in the face of opposition. So, you can either stand behind the US (like Blair did with Iraq), try to stand in front and stop it (no one's stupid enough to do that), or stand at the side and criticize (most of the rest).
Infamous dear boy, infamous.