Finally I found a permanent home for geoTwitter where you can check out the Alpha 0.1 and of course follow me at Twitter. To stay up to date with GeoTwitter news subscribe to the feed.
GeoTwitter is being hosted by Hostingfest, a extremely cheap yet good hoster. I can't believe they are still there.
GeoTwitter is open source and the project can be found here.
I have received already quite a lot of feedback, even bad feedback was actually good for me. Just to answer your questions:
I would recommend you to download the source code from CodePlex and improve it yourself, you can always check in the code.
Thanks for the feedback.