Are you asking because you operate an exchange or want to see this coin on one of the major exchanges?

Usually it's not the dev responsibility, but rather the specific exchange operators who want to add the coin to their exchange.
Exchange operators will add coins to their site if there are a lot of requests for that coin (They'll want to capitalize on the coin market. the bigger the better)

So, tweet away to your preferred exchange about SignatureCoin.

P.S
I know I'm coming off a bit as Captain obvious to some of you ppl. but there are a lot of new guys over here and I thought I can clear that out.