I dont think Osama wants a one on one battle with America, nor does he want to attack America with a force, what he wants and has always wanted was for the USA, and other western forces to leave the religious lands. You and everyone else has seen the problems that Iraq has put up for the USA. Just the iraqi's with the help of a few others have dragged on for a LONG time what was supposed to be a sweep. If he or anyone else united all the Muslim forces and just focused on getting the western influence out of the middle east, I dont think the United States could do much. Pakistan does have a pretty good fighting force, the 3rd largest muslim population has quite a healthy number of active military. And you fail to forget that there are many muslims that also live in countries that may not seem muslim. France has a large minority, India has the 2nd largest muslim population If somoene could convince even a percentage of those to fight under the same banner, then you can see the problems that the US would face not only occupying Iraq and Afghanistan, but also just having any presence in that area. Sure there are many allies in that area, especially Israel, and India. And the muslim countries would be surrounded, but I highly doubt that it would be an easy win for any western power to try to take over those countries on their home turf.
I would add that with unity comes strength and not just in a military sense....Egypt and Syria united from 1958-1961 and formed the United Arab Republic under the banner of Pan-Arabism....Guinea-Bassau (sp?), Ghana, and the Congo also formed a union under the banner of Pan-Africanism and there's also the African Union now as well...the best example would be the Arab states uniting in the 1973 Arab-Israeli War and putting an oil embargo on the US for its support of Israel, which hurt America economically...so Pan-Islamic unity is definitely a possibility.
Iraq is not causing us any problems militarily. Pointing to Iraq and saying, see this is what the Muslims can do is an argument against what you are saying. Occupying any country, especially if you are trying to do it the way the US is, is tough, but it is not a matter of a military problem. It is the same problems we had in Vietnam, and we would have in any other country in the world. We have put our people in a situation where we are asking them not to go after the enemy, but to sit around and wait for the enemy to come after them. That is far different than what I was talking about, and is far different from the US maintaining a presence in the Mid-East. Even if we did not remain in any of the Muslim countries, there is always Israel. Now, if Osama wanted to unite all the worlds Muslims in an effort to have the US not station troops in any Muslim countires (not what the original post or any of the others were about) that could be done with tactics that we see in Iraq, it also would not require any kind of pan-Muslim support, just a good supply of suicide attackers and the patience to wait out the American people. On the other hand, if Osama/the Jihadists/whoever wanted to unite all Muslims and destroy/take over/eliminate the US, they would have about zero chance to do so. Even if you took every Muslim from every country and he or she took all equipment they regularly used with them, they would still have no chance. The United States military is virtually unbeatable in a direct engagement. The Iraqi military in 1991 was considered to be one of the strongest, certainly the strongest in the region, and the US basically had them beat before even commiting ground troops. I would be more concerned by a Russian or Chinese military attack than an attack by the entire Muslim world.
Not all muslims think like extremists fools like Bin laden, khamenie and other right wing lunies. most moderate and smarrt muslims in iran and i'm sure other parts of the world reject voilence and killing innocent individuals who havent commited any crime. suacide bombings will only inflame the situation. bloodshed breeds bloodshed.