The New York Times has an editorial ('A Citizen's Right') opposing voting for non-citizens. They mention that Mayor Mike Bloomberg is also opposed to it:

This page believes that it is in the nation's best interest to encourage people who live here permanently to become citizens and throw in their lot with the interests of the United States. Extending the most important benefits of citizenship to those who still hold their first allegiance to another country seems counterproductive.

On the other hand, the Houston Chronicle has a news article slanted towards voting by non-citizens ('Immigrants' voting rights becoming a major issue'). It should come as no surprise that "liberal" blogger TalkLeft supports non-citizen voting; see my excoriating comments here. I'm sure countries like Mexico and China would just love to have their citizens voting in our elections. I mean, more than they do so already.