Topics covered in Martin's article below...
However I did want to comment more specifically on the following insightful observation Martin wrote under:
What’s Hot and Recommended
Here's My Reply On How This Process Happens To High PageRank Profiles:
+Joshua Berg "You are correct about this and I have made a related observation. It is profiles with high PageRank whose posts will go to the "What's hot" list. Even if in some cases that profile's high PR does not yet show on the PR Toolbar because it hasn't updated for that quarter. We can tell it has high PR because of it's high interaction and linkbacks"...
"Now whether this is cause and effect could be debated, but in my opinion the PageRank of Google+'s content, is used as a G+ EdgeRank to show which fresh content will get the highest visibility in both overall streams and will make it to the What's Hot list."
"This spreads out a persons influence (or we should sayability to influence) over a longer period of time then a single, or small batch of highly popular posts. For example, when I started sharing a very popular series early on, it did not make it to the What's Hot lists, even though far exceeding the average numbers to do so. Simply because the profile was new and did not have a popular history, most likely expressed through that profile's PR."