Scaling of Twitter - What's the truth ?

Twitter, there might be very few web browsers who does not know about twitter. For the benefit of those few, Twitter is a micro-blogging service that allows users to send updates.
Twitter used to go down due to the page views load. There is been lot of discussions, questions regarding the scalability of the Twitter. And I too faced many people asking the scalability, capability of the Ruby on Rails (technology with which twitter was built) in building the web applications.

Twitter started as a side project and blew up fast, going from 0 to millions of page views within a few terrifying months. Early design decisions that worked well in the small melted under the crush of new users chirping tweets to all their friends. Web darling Ruby on Rails was fingered early for the scaling problems, but Blaine Cook, Twitter's lead architect, held Ruby blameless:

For us, it’s really about scaling horizontally - to that end, Rails and Ruby haven’t been stumbling blocks, compared to any other language or framework. The performance boosts associated with a “faster” language would give us a 10-20% improvement, but thanks to architectural changes that Ruby and Rails happily accommodated, Twitter is 10000% faster than it was in January.

Hope that clears some air around twitter discussions. Interestingly, there are quite a number of applications that are build around twitter gaining popularity.
twittervision, summize (twitter search) to name few.
Twitter was made very handy with lots useful tools/extensions on every platform that you can think of. From desktop to iphone users, the gadgets are available here.
I too tweet here!
Few slides that comes handy when you want to speak/read, how the scaling of twitter is getting improved.
View/Download From Slideshare.
Scaling-twitter by Blaine
Scaling-twitter @ railsconf-2007