Twitter is continuing to gain more and more traction as more people than ever are now joining the social network. A very big important milestone was reached today, a Twitter share button has now been added on all YouTube video pages in the top share list alongside with MySpace, Facebook, and now, Twitter.

You can now easily tweet a video with the video title and URL included in the tweet automatically. However, the URL is currently not shortened, but YouTube will be changing this in the near future. It is also rumored YouTube may create its own URL shortening feature to accommodate the change.

Although growing quickly, Twitter’s hasn’t really established its business model yet. Twitter founder Biz Stone recently told the WSJ that premium services are under development and will be available by the end of 2009. Stone also said that Twitter has hired a product manager to oversee the development and monetization of commercial accounts. He went on to say that all existing features will remain free of charge for everyone, including for companies, but other premium features could be added for a fee. Twitter has yet to disclose any premium features under development.

The most recent VC round of investment valued the company at $255 million.

In more Twitter news, the company has now confirmed it will start offering free SMS usage for Vodafone customers in the UK.

In more YouTube news, the social video-sharing site today launched YouTube EDU, an educational section of the site focused on helping you find and watch educational content that is uploaded by educational institutions such as MIT. Videos include lectures to events, among an assortment of other videos. YouTube is set to officially launch YouTube EDU tomorrow.