Have a look at the source. There is a source link at the top-right on
Both input fields are free-form. You can put a city name, a zip code or a full address in the Location field and in the What field you put what you are looking for. There is a special hack that checks for something like 4* and the filters the results to only show you those entries that were rated 4* or higher on Yahoo! Local. You can of course also just put something like "pizza" or "mexican" in that field.
and people are discussing it here:
In my last entry I showed how to parse a geocoded XML file and put markers for each entry on the map. Someone asked me how I would do the using the JS-DHTML API instead of the JS-Flash API. It's a whole lot harder in DHTML, but it works. You can see it here:
And I talk a bit about it here: