nope. bitmessage uses proof of work as a spam limiter (like hashcash) and dht for connecting nodes. Bitmessage blocks have a limited lifespan and are deleted after their TTL expires.
I could be wrong but I am fairly sure it preceded Bitcoin by not very long. It is basically blockchain but not immutable.
CORRECTION: the design was based on bitcoin. But it is not built on the blockchain.
Well here it is for ya:
https://github.com/tidwall/tile38
that looks interesting but I wasn't thinking of it being precise location or even verified. Just as a way to quickly discover where steemians nearby might be who you can visit or gather with.