Markdown works for comments.
You might want to add a line and a blank line though between different markdown styles or it it might get mixed up and the codes will become visible.
A perfect markdown for the steem-bounty comment for instance should be as shown below. Aligned to the center with smaller but bold fonts.
@knircky has set 1.000 STEEM bounty on this post!
What is a bounty exactly A bounty is money sent to a post to be distributed to the users commenting on it. It provides a way to reward users directly on top of the steem/sbd they get from the blockchain independently of SP.
You create a bounty by sending any amount of sbd/steem to @steem-bounty together with a post-url in the memo. Users are then competing for the bounty by writing their answers to the post in comments hoping for upvotes from the community and especially the bounty creator. The money of the bounty gets distributed to all top level comments of the post at the same time when the post is paid out (7 Days after it was written). How much everyone gets depends on the votes the comments received. The sender of the bounties votes are weighted higher so that she decideds where 80% of the money goes and all other votes determine the rest. @steem-bounty does all of this for you automatically.
You can use this service to automatically pay out a challenge, ask a hard question or simply to reward the people that interact with you. Read more about how it works, even in different languages here.