There has been a lot of noise in the last few weeks about how Twitter’s growth, particularly in the US, has levelled off.

But new research from Sysomos reveals that in the rest of the world at least, the micro-blogging service is as popular as ever.

The study, conducted during October and December 2009 found that the number of US unique users was 50.8%, a sharp drop from 62.1% in June 2009 – suggesting that there has been significant growth elsewhere in the globe:

“For location, the most significant difference in users was a surge in Brazil, which accounted for 8.8% of unique users, an increase of more than four-fold from 2% in June. Twitter users in Indonesia accounted for 2.4% of the population, compared with less than 0.5%, while Twitter users in Germany rose to 2.5% from 1.5%.”

When cities were examined, London still leads the way with the biggest population in terms of unique users (2.08%), while Los Angeles has 1.63%, Sao Paulo (1.47%), New York (1.44%) and Chicago (1.2%). Despite London’s lead in terms of users, the UK capital is pipped by New Yorkers when it comes to the number of tweets generated – make what you will of that one!

These are interesting statistics, but what can we learn? It seems that the rest of the world is really getting the micro-blogging bug and usage is certainly increasing outside the US. Detractors point to the fact that usage in the US is actually slowing quickly, but as all good PRs know, it’s not necessarily about the numbers, but the power of the influencers in the audience that really matters.