I don't think git is going to magically draw more contributors to a project, but it certainly does make the lives of everyone involved with the project easier.
Even if you end up with the same number of contributions when compared to svn, I still think git is worth the switch. Being able to add a remote repository and cherry-pick a specific patch, or merge a branch in a matter of minutes is great. I don't maintain any popular projects, but for the few that I do get contributions, it has made my job much quicker and simpler.
As much as I think a more a uniform style and message would be great for Perl, I also think that releasing and marketing an application that non-Perl people would find cool and useful could do as much to fix Perl's image problem as anything else.
After using this fictional application, a user might see that it is written in Perl and think "Hey, I didn't know that Perl can do that". They might then look at the source code and think, "Hey, this isn't the same ugly Perl that I remember from the mid 90s."
A good example of this for me was Rails. When Rails was released I didn't know much about Ruby, but that one project prompted me to look into the language. It wasn't the marketing coming out of the Ruby camp that inspired me so much as the cool things you could do with Rails and clear messaging on the Rail's website.