The Key Value Lookup Column add-on now uses native keys (e.g. a Customer ID) for lookup values to another SharePoint list. To ensure integrity not the SharePoint Item ID is used (like with SharePoint out-of-the-box lookup) but the foreign key itself. That solves many issues with SharePoint standard lookups, e.g. with deployment and updates.
Full Specifications
What's new in version 1.0
General
ReleaseMay 28, 2011
Date AddedMay 28, 2011
Version1.0
Operating Systems
Operating SystemsWindows 2003, Windows 2000, Windows Vista, Windows 98, Windows Me, Windows, Windows NT, Windows 7, Windows XP