The social space online changes rapidly. Feedback stays on top of emerging media news so you don’t have to. Here are the must-read social media articles of the week for the week of October 16th.

Active Tweeters
At the Web2.0 Summit Twitter CEO Dick Costolo shared statistics on active users. Twitter now has 100 million month active users, and of those 50% log in everyday. Twitter isn’t catching up to Facebook just yet. Facebook has more than 800 million active users, and of those 50% log in everyday.

iPhone 4$:
With a dual-core AA5 chip, new camera and optics, iCloud and Siri (Apple’s voice recognition app), the iPhone 4S is pretty impressive. Sales for the newest iPhone are pretty impressive as well. Let’s look back a bit: it took 74 days to sell the first million iPhone’s and it took three weeks to sell three million iPhone 4′s.

Drumroll, please.

It only took one weekend to sell 4 million iPhone 4S’, making a new iPhone sales record.

Now, for those of you who don’t have it yet, the question is “To upgrade or not to upgrade?”

Social & Mobile
Highlights from a recent ComScore Study:

Those using social networks from their mobile device grew 37% in the past year and more than half accessed social networks almost every day.

Facebook’s mobile audience is approaching 60 million users. In the past year, mobile posts grew by 50% on Facebook,  75% on Twitter and 69% on LinkedIn.

70% of mobile social networkers posted a status update from their phone and the majority of them read posts from brands from their device.

“Social Jobs”
Facebook and the Department of Labor are working together to connect job-seekers and employers through Facebook. Called Social Jobs,  “The partnership’s goal will be to facilitate employment for America’s jobless through the use of social networks.” Social Jobs aims to provide job postings and resources for job-seekers and recruiters. Like “Social Jobs Partnership” on Facebook to learn more: https://www.facebook.com/socialjobs. (With never-ending privacy issues, I wonder if people will be weary of “Social Jobs” as many don’t want potential employers seeing any part of their Facebook life.)

Are You LinkedIn with your Classmates?
While Facebook was adding features to help users find jobs, LinkedIn was busy adding a feature to help users expand their network. “LinkedIn Classmates” is a new feature that makes it easier to connect with alumni from your college/university. As LinkedIn described,  “In the years since college, your classmates have become experienced professionals, industry experts, potential clients and trusted colleagues – in short, people who can help you expand your horizons.” This new tool allows you to see where alumni work, what they do, and where they live. You can also see what you have in common now, making it easier to network and connect with them.

-Anna (@alucas9)