[Banshee-List] Why Catalog.GetString()?

[Brandon Perry <brandon thresholdofthought com>]

I am writing a small plugin for Banshee just to learn some of the ins
and outs of Banshee and am using the others as kind of a base. Perusing
through the code, I found that Aaron declares his buttons as such:

Button create_account_button = new Button(Catalog.GetString("Create an
account"));

Is there a reason to use Catalog.GetString() instead of just a plain
string?