It’s hard to imagine the giant undergoing anything like a slump. It just doesn’t happen. Half the Facebook jokes that are out there are about how there’s no stopping this thing.

And yet, it happened. After posting 7.8 million new users in May, the expansion dropped to just 328,000 new users in June. But not to worry. The social media apocalypse is not upon us. They added another three million in July. Just like that. Social media is still here to stay, and social media marketing is still a big deal and you still need to care about it if you want to stay relevant.

After all, another huge milestone has occurred. Facebook has just hit 500 million users. Only 125 million of them are here in the US, to be sure, but this is no reason to panic. This country still represents the biggest ad market for the entire site.

What’s interesting to note, however, is where the fall-off came from. It wasn’t a bunch of older users who just decided that enough was enough. The big drop off actually came from the 18-25 crowd; it was significant enough that they actually lost users from this demographic rather than experiencing a net gain. If anything, the older crowd actually grew.

Women still outnumber the men, even though the men led the growth trends throughout July. The Inside Facebook blog offers several ways to interpret the data:

These broad trends suggest several ways to read July’s growth. One is that Facebook’s audience is simply becoming more reflective of the overall population over time… Early on, Facebook was dominated by users ages 18-34 and had more women then men.

It is also possible that some of the users were lost on account of disagreements over Facebook’s privacy policy. Another possibility that they offered is “Facebook Fatigue” – that is, that users are just getting worn out from the constant connection with each other.

What does that mean for you as an internet marketing force? It means that there’s more pressure on you to make yourselves and your products stand out. If people are getting tired of the way things have been done forever, then the burden is on you to change the game up a bit. You can’t just set up a Facebook page, an email marketing bot and watch the money roll in. It’s not going to happen, especially if users are genuinely tired of using Facebook for interactions.

And what a time to do it. Facebook is achieving saturation status in the US market – it has a 42.1% penetration into the country’s population. Now it’s time for them to expand out into the rest of the world. Even if there should be losses in the US market, Inside Facebook notes that the cmpany can easily offset these losses with gains worldwide.

The June blip can be ignored. The overall trend is growth. And that means challenge for you marketers out there.

But let’s face it – if there wasn’t a challenge here, what fun would it be?