At the Web 2.0 Summit in San Francisco, Twitter CEO Dick Costolo has revealed an interesting milestone. Twitter is now hitting 250 million tweets per day. Twitter has gone from 90 million tweets per day in September 2010 to 100 million at the beginning of the year. Now Twitter is at 250 million, which is a 177% change.

The White House has uploaded some images on Flickr of President Barack Obama’s meeting with the tech titans of Silicon Valley. This photo symbolizes how the meeting went. The meeting was about how these executives plan to support entrepreneurship, increase exports, and strengthen the economy. The executives in this picture includes:

President Barack Obama is making a trip to Silicon Valley today and is meeting with some major tech CEOs. The names of the executives that he is meeting was revealed by the L.A. Times. The meeting will be about supporting entrepreneurship, increasing exports, strengthening the economy, etc. Below is the list of people that he is meeting:

Microsoft Corporation (NASDAQ:MSFT) CEO Steve Ballmer and Twitter CEO Dick Costolo was rumored to have had breakfast together in San Francisco earlier this week as reported by Forbes. “Could this mean Microsoft is interested in doing some sort of deal with, or even buying, Twitter?” said Forbes writer Victoria Barret. Yes, Twitter is the hot property that everybody wants a piece of right now. And yes, Microsoft attempted to buy out Facebook and Yahoo! to grow their web portfolio. Maybe Ballmer was in the area and wanted to talk to Costolo about how their Bing and Twitter partnership is going.

Dick Costolo was interviewed in the Telegraph UK where he discussed what his role as the newly appointed Twitter CEO is. When asked what the long term vision of Twitter is, Costolo said “I am working on clarity around that at the moment. I am currently trying to define what Twitter’s purpose is in the long term. We will be able to be more specific on that answer in the near future.”

Twitter co-founder Evan Williams has asked Dick Costolo to become CEO of the company. This way Williams can focus more on the product. Currently Twitter has 300 employees. There was about 20 employees two years ago when Williams took the CEO job at Twitter.

Twitter is selling promoted tweets for $100,000 each and higher. However marketing companies are pondering whether the investment has been worth it. Currently advertising on Twitter is considered as an “experiment.” Best Buy and Pepsi tested out the ads already, but have not bought ads again and about 80% of the companies that bought an ad have not bought any more.

Micro-blogging company Twitter has hired Adam Bain to be the head of their revenues department. Adam Bain will be reporting to Twitter COO Dick Costolo.