How can I find a list of fields output by a view block?
You're using the 'row style' type 'fields' here, correct? The field you are grouping on should also be added as a field in your 'fields' list in order for this to be showing correctly in your preview so all you need to do is find the name, which can be tricky to guess depending on the cck field type. One way you can do this is by hovering over the 'link' in the fields editor within views:



and get the name of the field from the url in your browser status bar, ex. 

../view_name/display/field/&lt;your field name&gt;


and then you just print out the rendered view content of your field in your tpl with:

&lt;?php print $fields['&lt;your_field_name&gt;']-&gt;content; ?&gt;