In fact these celebrations reminded me very much of a scripture:
Now, they [the more righteous people] were sorry to take up arms against the Lamanites [the ones who are blood thirsty], because they did not delight in the shedding of blood; yea, and this was not all—they were sorry to be the means of sending so many of their brethren out of this world into an eternal world, unprepared to meet their God. (Alma 48:23)
This scripture is from the Book of Mormon, which is basically an account of a family that lived in the Americas long before it was ever colonized (in other words the ancestors of the Mayans and Inkas, etc.). Their family divided themselves up into Nephites, who believed in God and tried to keep his commandments, and Lamanites, who were constantly seeking to destroy the Nephites, because they felt wronged by them. This scriptures refers to a massive war in which the Lamanites were seeking to infiltrate and overtake the Nephite cities. At this point in time they didn't succeed, but eventually the Nephites became so prideful and unrighteous, thinking themselves better than everyone else, that they did in fact get completely destroyed.
I see a parallel to what is going on today. Don't get me wrong. I'm glad that Osama is no longer running around planning killings, and I'm not saying anything against the fact that he was killed. I'm not opposed to taking actions to defend and protect life. But evil hasn't stopped because of it. There is a difference between defending to protect, and gloating revenge. When we gloat, and celebrate we are allowing some of that same evil, the complete disregard for the sanctity of human life, into our own hearts. There will always be evil as long as we rejoice over taking someone's life, as long as we think we are better than others. And it doesn't matter who is doing the celebrating and gloating. A life is a life.