So I uploaded the widget on friday evening, and they only post new widgets on weekdays, so it went online yesterday afternoon. Today, there were several comments with vague comments about a load error (nobody actually bothered to specify what the error was). Since my desktop at work is Linux, I couldn't try it out there. I did notice that the USGS had redesigned the layout of their Earthquakes web site. The RSS feed seemed fine, though.
When I came home I found that my widget at home didn't work either. Further investigation showed that the USGS had set up a redirect from the old RSS URL to the new one, but the widget engine wasn't smart enough to automatically follow the redirect. So, I fixed the RSS URLs that it uses.
Furthermore, the RSS feed has links to the web pages for each specific earthquake. This is used by the widget to open a browser window when you request more info by double-clicking on the earthquake circle. However, the RSS feed currently points to .htm versions of the earthquake info pages - but they are now .php. I coded a workaround to simply strip off the ".htm" extension if present, because it appears that the pages work without having to explicitly include the extension.
Anyway, how frustrating that the very next day after uploading a shiny new widget to the gallery, and after over 3000 downloads, the USGS switches over to a new web site that breaks the widget. Oh well, I'll upload a fixed one right now that Yahoo should post tomorrow, that should be more resilient in the face of future changes.