The Lisbon Treaty in the EU finally cleared one of its biggest hurdles today--that set up by the voters of Ireland.
Requiring unanimous approval of the member states of the EU, the Lisbon Treaty was signed by heads of state of all 27 member nations in 2007, and was expected to be in force at the beginning of this year. For all but Ireland, national parliaments rubber-stamped the treaty through (though the Czech and Polish executives had refused to sign the treaty until the Irish passed it--not sure what they've done yet). With the Irish vote done, the treaty is likely only some red tape away from coming into effect.
The Treaty would strengthen the breadth of powers and autonomy of the EU parliament and executive, create tighter central integration, and a whole bunch of other stuff. In reality, it's very similar to the "EU Constitution" which was so summarily rejected by the more nationalist nations of France and Holland before being abandoned entirely. While the Treaty of Lisbon's passing does not actually make Europe one big happy sovereign nation, it does make it pretty darn powerful (they'll even have a single Foreign Minister to represent the "united" EU opinion on foreign policy). It's the kind of treaty that makes an old-school realist sit down and wonder what sovereignty really means.
If the EU holds together and chugs forward, I anticipate some level of "de facto" sovereignty will emerge, even if it is not formalised in the lifetimes of anyone around today. Many of my European friends (with very strong nationalism) would surely want to cut my tongue out for saying such a thing, but I will indeed note that state pride/nationalism in the US was incredibly powerful until after the civil war (if you've seen any of those civil war movies, you see the Confederates holding up state flags and screaming things like "FOR VIRGINIA!"). In fact, while the States of the US did not have formal sovereignty in the Westphalia sense as soon as the Constitution was signed (they essentially retained their sovereignty under the Articles of Confederation by... oh, just go look it up if you don't know), the de-facto erosion of state-level power, autonomy, and semi-sovereignty is obvious in American history. Every time some issue emerges that is pressing enough to worry some majority of the country, the voting public cedes another notch of power to the federal government (though I will remain mum on whether this is or isn't a good idea).
My point is that the creation of a centralized confederation for all of Europe is similar enough to the confederation of the American states that I think a somewhat similar process of growth of central power is relatively inevitable unless the formalized central system is reversed, and quickly (which is highly unlikely).
I believe, though, that the situation is more likely to be reversible than in the US, and I believe that Russia has the potential to cause it. Like George Friedman (by the way: go read The Next 100 Years), I believe that the nations of Europe have such a vast discrepancy of fears and misgiving's about Russia's potential behavior and future that its expansion and aggression is more likely to drive a wedge between European countries rather than unite them. If Western Europe does indeed abandon the East in order to keep the oil and gas flowing, then NATO will become defunct, as will any faint illusion of collective defense in Europe under the umbrella of the EU. And then, expect some action.
But until that hypothetical arises, expect the EU to be a rather happy-go-lucky place for a while. Maybe (just maybe) it will become a more assertive and significant player in world affairs, after a 50-year post-world war II hiatus.