When it originally filed its S-1 documents ahead of its listing on the stock market, Facebook conceded that its inability to monetise its mobile platforms was the biggest challenge it faced.

So, it’s perhaps not surprising that just days before its initial public offering in New York, the social media networking giant has released subtle but telling updates to its mobile services.

The most obvious change is the size of images on Facebook’s iOS, Android and mobile Web versions. Where images were previously thumbnails in its news feed, and bordered with black in single-image view, they now stretch almost to the edge of the screen.

Mobile needs to be visually heavy rather than text heavy and it appears Facebook is ensuring it mirrors this. It also means the introduction of small banner advertisements or similar intrusions could be less noticeable or off-putting once users have become accustomed to an image-heavier Facebook.

The company has recently made a handful of acquisitions that also hint at its desire to increase its abilities in mobile. Last month, it acquired mobile photo-sharing application Instagram for a mammoth and headline-grabbing US$1bn in cash and stock. Glancee, a location-based app for finding people with similar interests, followed this deal.

Facebook also bought TagFile, a marketing and customer rewards tool and, of the three acquisitions, it’s the most obviously monetisable. Glancee and Instagram feel more like talent grabs and exercises in preventing other companies from acquiring them first.

Facebook, led by its youthful CEO Mark Zuckerberg, is becoming dominant as a portal to the Internet on desktops with its ever-increasing ways to keep users from actually leaving its ecosystem, even when looking at external links or videos. Now Zuckerberg and his troops needs to figure out how to do the same for mobile.