Anything is possible!
If you are repeating out the BlogPosts, and you just need a "count" of how many items are in your repeater, you can use the <%# DataItemCount %> or {% DataItemCount %} (depending on what transformation type). This gives the number of items being transformed.
Otherwise Kentico is database driven, which means you can easily create a query that will get that count, and reference it.
For simplicity sake, you may want to leverage the Text/xml transformation type (so you can use kentico macros), then use the following macro:
{% Queries["blog.comment.selectall"].Where("CommentApproved = 1").Count |(identity)GlobalAdministrator%}
I couldn't really test the above but that should do the trick.