Patch 4: minTest option 

--- jquery.autocomplete.js      2009-08-10 13:02:21.000000000 +1200
+++ jquery.autocomplete.js      2009-08-10 15:59:38.000000000 +1200
@@ -248,7 +248,7 @@
                previousValue = currentValue;
                
                currentValue = lastWord(currentValue);
-               if ( currentValue.length >= options.minChars) {
+               if ( options.minTest ? options.minTest(currentValue) : currentValue.length >= options.minChars) {
                        $input.addClass(options.loadingClass);
                        if (!options.matchCase)
                                currentValue = currentValue.toLowerCase();