I don't think simply breakng 50% is popular.
For a politcally divided country, it's a good sign. With a large majority of the Democratic population in the country refusing to give Bush any credit at all, you can't get much more than 55-60% (assuming 100% of the Republican and Indepenent/3rd Party members do put their support behind him). However, I go back to what I said earlier . . . it's history that will show how good/bad he was as a President. Popularity polls tend to be much more erratic that historical reflection.
Bill Clinton left office with a near 60% approval rating in this allegedly divided country after having embarrassed himself repeatedly and publicly. I simply can't accept the idea that the country is too divided to have someone more popular than 50% or so. Its the fact the George Bush isn't any good at his job anymore that's driving down his approval.
If people knew that the economy was starting to tank and that we were about to get hit with the largest terrorist attack on US soil, I bet his numbers would not have been so high.
Plus, I remember that they continued doing Clinton approval polls the first couple months Bush was in office and his numbers sunk to about 50% because of "Pardongate".