It would be better to make a quick module to do this because its really processing logic rather than layout/design logic, but you can do this:
{jrCore_list module="jrBlog" limit="500" search="blog_category in featured,latest" template="null" assign="rows" return_keys="_item_id"}
{if is_array($rows)}
{foreach $rows as $row}
{$_ids[$row._item_id] = $row._item_id}
{/foreach}
{$wanted = implode(',', $_ids)}
{/if}
{jrCore_list module="jrComment" order_by="_created desc" limit="10" search="comment_module = jrBlog" search1="comment_item_id in $wanted"}
We cant get blog_* because we're searching on the Comment datastore and that info just isn't there. What is there is the item ids of the blogs, so first we get a list of item id's that correspond to the categories you are after.
We then reduce that list down to the distinct values using that foreach loop, then we ask for the comments where the comment_item_id is in the list of the ones that we want.
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I reckon a better way would be to make a small utility module that you can use for tweaks
/modules/gmTweaks/
and add in a smarty_function_gmTweaks_comment($params, $smarty) and do the same thing in there in stead.
That way the template would just look like
{gmTweaks_comment category="featured,latest"}
Bit cleaner, but does the same thing.
