If you are running a script that makes use of the eBay RSS product feed. Take note that from next month (June 2012), support for the RSS 1.0 format will be discontinued.
So scripts that parse the content of the feed will need to use the new feed URL, and support the new format of the data in the eBay RSS 2.0 feed.
This will affect sites built with BANs, and eBay plugins etc. Likely effects of not upgrading are: your site may display an error message (because the new feed can't be accessed), and/or show blanks where the products are supposed to be displayed.
For developers: to check out the changes, I recommend logging into your eBay Partner Network account, generating an RSS feed URL in the Tools section, and downloading the results to check out what data you get returned.
In an ideal world, you would download developer docs, or read the API documentation.
At the last minute, the owner of BANS (Build A Niche Store) sent details of an upgrade to the script to existing owners, so BANs is covered for the transition to RSS 2.