Hey,
It might be interesting feature, however it's not possible with current Steem API (or not simple and efficient). There is reblogged_by field in post, but it's empty most of the time (it has one username when loaded in feed).
However it might be possible in the feature, when we migrate to our own API solution.
RE: Suggestion For Busy.org: Apart from showing on the feed page, sharers (I.e 'resteemers') of post links should also show on the author's blog page at a glance — make it happen