What is This? OS X Yosemite Shows iOS Apps in the Dock

I turned on my MacBook Pro this morning when I got to my office and noticed a second Mail icon in what appears to be a separate dock, curious as to why it was there, I hovered over it and the text read: Mail From Jeff Weisbein’s iPhone.

What?  How and why did that even show up?  I’m still not 100 percent sure, but from what I have been able to tell the additional icon and dock show up when certain apps are opened on my iPhone.

When I turned on my Mac, I had Mail open on my iPhone so it seems that is why it showed up.  I tried a few different apps including Calendar, Contacts, Weather, and other non-Apple apps — the whole thing seems to be kind of hit or miss.  When I clicked on the Mail icon it just opened the regular OS X Mail client, so it could be a way to offer quick access and additional continuity between iOS and OS X.

If you have any information on this, please leave a comment.  In the mean time, I’ll keep playing around and digging for more details.