Thanks for the quick response.
Something weird is going on with WordPress' servers. Stuff like this has happened before apparently:
I'll try whipping up a quick 3.0.10 release to see if that nudges the WordPress SVN server to process the plugin correctly.
In the meantime, you can download the latest version of wpStoreCart from this working link:
1. Download wpStoreCart zip file: http://downloads.wordpress.org/plugin/wpstorecart.zip
2. Extract the “wpstorecart” folder from the zip file you downloaded, to your desktop.
3. Use a FTP program to connect to your webhost and change directories to the /wp-content/plugins/ folder inside your WordPress installation folder. If you do not have an FTP program, we recommend the free and open source Filezilla for Windows. http://filezilla-project.org/download.php
4. Click and drag the entire “wpstorecart” folder from your desktop, into the /wp-content/plugins/ folder in your FTP application. Not all applications support drag and drop, so you may need to upload the “wpstorecart” folder to the /wp-content/plugins/ directory another way. Consult your FTP programs documentation for details on uploading folders.