For those of you that have asked, our new "key-free" search form uses the Google Maps API v3. Google decided to drop support for IE6 with version 3 so our new search form does not work with IE6. However, we still include the older form which uses Google Maps API v2 (and a key) if you need to support IE6. The non-javascript enabled search form should support almost any browser.
Eventually we will drop support for IE6 altogether. So encourage your customers to upgrade their browsers.