Ok, I admit that I am seriously considering making an offer on a Brewers Hill condo, so I'm not exactly disinterested, but shouldn't the left think gentrification - at least in moderation - is a good thing? Shouldn't Michael McGee, Jr. think rising property values are a boon and not a problem?
Remember if you are an urban liberal, you believe that it is possible for the government to create prosperity. You think it is possible to tax your way to economic revitalization. So why wouldn't you want a brand new source of tax dollars?
Gentrified urban neighborhoods generally involve households without children. They don't use the schools and don't make demands upon the social welfare system. They may demand some additional police presence (although the fact that they need to is an indictment of the manner in which poor neighborhoods are policed), but, generally speaking, we are talking a huge net "revenue enhancement" which can now be spent on the rest of those ungentrified neighborhoods.
And since you think government spending is a good thing, why not welcome the new vistas that have now been set before you?
It seems the folks that would be most opposed to gentrification are the crunchy cons, but they often seem to be the very people who are doing it.