Summer is one thing, but September is the month when everyone comes back to work, when the IT industry wakes up and when things, generally, start happening. A bump in the stats of almost everything that's online is natural, so Facebook's meager 1.96% growth when it comes to unique visitors isn't something you'd write home about.
There's a difference between these two, however: Facebook is already huge; there's always a question of whether it has room for further growth at all. Twitter is several orders of magnitude smaller; accustomed to its explosive growth, we've already started calling it the "new SMS", but if it stays where it is, numbers-wise, it's not going to cut it. In September, its unique visitors fell by 0.17%, to 23,538,791. Over the last three months, it has grown approximately three times less than in May alone.
Furthermore, if we look at visits, Facebook experienced a solid 3.99% increase to 2,290,512,524, but Twitter actually dropped by a further 2.68% to 144,661,590. This doesn't look too bad until you remember that Twitter's growth in the last three months has been a staggering 463.62%.
When it comes to other social networking powerhouses of old, the situation is far, far worse. MySpace and Bebo are bleeding users at an oustanding pace: 11.15% and 15.41%, respectively. If the trend continues, we might see these sites join services like GeoCities in the geek history books in a couple of years.
We've noticed, however, that LinkedIn has been steadily growing lately, and the trend continued into September, with the service recording a solid +5.68% growth. Finally, we've noticed last month that Digg's numbers look excellent, but in September, they remained almost the same with a tiny 0.25% growth to 43,888,259 uniques.
Judging by these (very diverse) numbers, I have a feeling that the period ahead of us will be different than before. Users are getting picky about what they want; they're very fast to jump on and off bandwagons, and the movements in the social networking space are getting harder and harder to predict.
A good example is another social media darling that recently got sold to Facebook: FriendFeed. Once touted as the next big thing, it seems to have sold at just the right time, as Compete's numbers show a huge drop in both unique visitors (-28.41%) and visits (-27.96%). A couple more months, and it might completely drop off the charts.