You need to look no further than my own timeline to see it. I have 287 people in my circles that I follow. Most are extremely active on other networks - Facebook, Twitter, etc.. A large number of them have Android phones, so are presumably automatically uploading their photos and videos for sharing as I do.
And yet, with those 287 people I follow, there is exactly one update in my timeline this afternoon that's not from myself sharing with other people.
On Facebook, I have 500 friends and have received dozens of updates during that time. On Twitter, I follow 187 people--less people than on G+--and have two dozen updates.
The stat that Google keeps giving is "number of people on G+". Sorry, number of people on G+ doesn't matter. Everyone with a Gmail or Picasa account is basically being opted in, and no one uses it. Most of my IRL Google friends don't even use it.
G+ is a huge failure. The biggest social network no one uses. It's so obvious it's not even funny. They've been trying to do what Twitter has done and what Facebook has done -- i.e. being feature equivalent. G+ is proof that that plan doesn't work. How many times has Microsoft tried this strategy and failed? (Bing? Zune?)
First, stop taking away the services we like and folding them into G+. We liked PicasaWeb. But now that's it's gone, my family entirely switched to using Smugmug. Making this change had the opposite effect than what Google intended.
The second answer is focus on the things you have that are novel. The most novel feature of G+ so far is Hangouts. It's what draws people to G+ more than anything: Hang out with Obama, etc. Figure out how to rally around this with the audience you have. What about tying it into Google Voice? What about making the quality crazy-high and taking on Cisco? What about doing presentations with it? THINK. Think of things you can do to rally around this, because no one is looking at people's non-updates on the thing and this is the ONLY novel thing G+ has.
The other thing Google shouldn't be doing is putting G+ in everyone's face every day -- at least for now. It's almost counter-productive when people are sign up and then never use something. In their minds, they tried it, didn't like it, and getting them to come back is even harder than having them come the first time.
In the mean time, I'll have to suffer through Facebook's completely broken Ice Cream Sandwich experience.
[Update]: As if you need any more evidence, Google has now added "What's hot on G+" entries to my timeline that I didn't subscribe to. Because there's such a dearth of updates, they have to throw in stuff.