As the tech press (and Diane Sawyer) prepare for the imminent, champagne-filled announcement of Facebook eclipsing the 500 million user barrier, we hate to be killjoys here at SMI but we feel it necessary to point out that the first 500 million, that was the easy part. For Facebook, the vast unconquered terrain lies in China, Japan, Korea and Russian-speaking countries where Facebook is an also-ran.

The mobile apps marketplace will top a staggering 25 billion downloads by 2015, according to new research by Juniper Research. To put that in further perspective: the estimate is that smart phone sales will reach 1 billion annually by the same period. That’s an impressive number of downloads per handset user.

Twitter is certainly banking on making money, and doing so soon. The company’s chief operating officer Dick Costolo told Reuters he expects no less than “hundreds of advertisers” to start paying for prime real estate on the micro-blogging platform’s by the fourth quarter of this year. A bold prediction, or a lot of hot air?

Google and Microsoft are making moves to reorganize the way we use email. It comes at a stage when we’re using social networks more and more in favor of the old email inbox. Why then all the fuss and investment? And, what does it mean for us?

Google launched in the U.S. earlier this year its own iPhone killer, the Nexus One Android. The launch plan centered on a bold step: selling the handset direct via its online shop.

Search engines handle well over 100 billion queries per month worldwide, and yet the experience of hunting down the relevant answer can still be such a frustration. For this reason, industry observers are now heralding social search, which promises to be more relevant and timely.

Recent numbers suggest that Facebook has surpassed Yahoo and Microsoft in number of display ads delivered. That’s the good news. Less inspiring, Facebook’s ad revenue is still lagging well behind competitors. While big players like Verizon, Toyota and Ford are taking the top ad spots on Facebook, it’s looking like Facebook’s success comes down to companies you’ve probably never heard of.

Wanted: mighty business power losing ground to upstart competitors seeks whiz to jumpstart its social media operation. A fluency in enterprise software, plus consumer-facing tools/applications a must. The ideal candidate is a persuasive communicator able to convince upper management that a Twitter feed and YouTube channel doesn’t mean you’re a social company. Interested applicants please apply to Google.

It was halfway through a conference presentation this week by Facebook that is dawned on me just how powerful the social network had become, just how big its own plans are and just how much it now has to lose.

Remember Google’s Nexus One? It’s set for European release on April 30th. Will it be met with praise, or will it suffer the fate of its American brother?