At the moment of writing, @musing has 1,071,501.805 Steem Power.
92.77% of the delegated Steem Power comes from Steemit Inc through their @misterdelegation account (The account used by Steemit Inc to support and power other platforms built on top of Steem).
While 75,396.997 SP comes from @roadscape, the guy famous for SteemD
Not quite sure about the other 999950SP, but they got the whole 50SP from me!!!😉
Musing got nearly all of their delegation by @misterdelegation, an account owned and managed by Steemit INC. for supporting dApps' accounts. Utopian-io, dtube, oracle-d and many others received hundreds of thousands of SP by Stinc (Steemit INC) in order to be able to build up a community, and to be able to spread rewards.
They got their delegation from steem inc.
Read this article for more information:
Ned hooked them up with his mister delegation account. Pretty sweet deal.
The delegation was given to Musing by Mr Delegator which is ab account belonging to Steemit Inc.
This delegation is to enable musing.io to grow and get on their feet. They make the rewards from curations on each vote they hand out. I don't know if they have a time limit or more will be added as it becomes more popular.
I think but not sure but SMT's for musing will be handed out or earned against their delegation.