Hi,
When I go through all the steps in “Package Extensions” and I click on “Save and create”, then I get an error: Unknown channel “magento-community”.
My version of Magento is 1.4.2.0.
Do you have version 1.4.2.0 or 1.4.2.0-rc1? The latter requires you use “community” channel field. Download the packaging guider here for more details. http://www.magentocommerce.com/magento-connect/create_your_extension/
If you are using Magento 1.5 or later to package your extension type: community
If you are using Magento 1.4 or prior to package your extension type: connect.magentocommerce.com/community