Of course this is an important milestone but in reality it amounts to just 4.4% of the browser market -- barely edging out Safari at 4.37%. Both browsers are still well behind Internet Explorer which sits under 64% and Firefox at around 25%. That said, it has taken five years for Mozilla's browser to get where it is today and going by these numbers the one year old Chrome is on a rising path.
The recently introduced extensions support in the beta and developer releases may have a bigger impact in terms of market share once it is officially rolled out to the final version. I for one was enticed enough to make Chrome my default browser and have been using it almost exclusively for the last week or so. While the selection is still rather limited, extensions seem to work really well and haven't impacted the browser's fast performance.
On a final note, just to offer some additional facts, looking at our own logs we were surprised to see Chrome usage grew 2.5% among TechSpot readers in the last month while Internet Explorer and Firefox saw a respective drop of 10.83% and 7.45%. Their total share stands at 43.42% for IE, 41.1% for Firefox, and 7.92% for Chrome.