No need to convert brushes anymore. Gimp vers. 2.6.10 and forward just load the PS brushes into the Gimp brushes folder like you would a regular Gimp brush and it will recognize it. Don't forget to refresh or restart Gimp so they will appear in the brushes toolbox!
I've tried everything I know and am still unable to convert a brush pack... I'm not sure what i'm doing wrong. Could someone help?? I'm trying to convert this pack: [link]