Believe it or not, there is only ONE Apple Aperture Flickr Export Plugin in the market right now which is ConnectedFlow's FlickrExport. It is a very simple plugin (and have some bugs) and the author charges us for £14 (about US$28). I think it's too expensive for a plugin like that.
Stop complaining, here is my version of Flickr export for Aperture. It is called Efania Faperturer. I'm still learning how to write Cocoa in Objective-C. The most difficult part is...there is not much documentations or discussions on the Internet about Cocoa or Aperture Plugin.
It is not fully functional right now so I don't decide to release any binaries for any public testing yet. Please stay tune....
By the way, since there is not much documents and/or discussions about programming Aperture plugin in Objective-C. I decide to blog the details about how I write this plugin.