From Changes from 4.5 to 5.0, in detail :
Sharing is the Jive 5 equivalent of (and more powerful replacement for) Send as email in 4.5. You can share content and places with others with the "Share" link, which opens a modal containing a form into which you can enter recipient(s) with whom to share. An item shared with you by another member will come to you in Communications, where you won't miss it. You can share a piece of content, or a place (a space, project, or group). You can share to one or more people (including a label of followed people), but you cannot share anything to/with a place. Also, one can respond to, and optionally continue a threaded conversation based on, the initial share notification. With this model we have a record of shared items; no more lost messages to people with whom you are sharing. The things you've shared are also in your Communications.
Are there any plans to expose these conversations in Mobile 2?
A co-worker just responded to a share I made yesterday and not seeing their response in Mobile makes it difficult to keep up my Community Management duties when on the road with iOS.
The mobile version of Jive 5 does not yet support the Communications stream. A portion of it is available, @ mentions, but the full read-tracked stream which includes direct messages, shares, mentions, and activity on your content will come in the 5.0.1 update to Mobile which is tentatively timed for the end of this quarter.