Twitter unveiled a new home page design today with an enhanced sidebar that displays images, video, and user profile information without leaving your news stream. The change is notable because Twitter.com is still the most popular way for people to use Twitter: fully 78 percent of all users access the service through the site.

At launch, media content partners include YouTube, Vimeo, Ustream, TwitPic, Flickr and 11 other firms, but Twitter is actively looking to expand its media partners. This content will appear in a sidebar beside a relatively traditional newsfeed.

The new design certainly has more components, but Twitter co-founder Evan Williams says he isn't worried about making the service overly complicated. "Embedding the media doesn't make Twitter more complicated," according to Williams. "It makes it simpler because you don't have to open up another link."

Williams says part of the reason for the design is to make it a better tool for consuming information. "You don't need to tweet to use Twitter, it can be a great way to just get information," Williams said. There are more than 90 million tweets a day on Twitter and about 25 percent of those tweets have links, he said.

William said they have tried to remove friction through the Twitter experience. "You can scroll endlessly down your feed, there is no more "More" button," William offers as an example.

The hastily called press conference was held at Twitter's headquarters in San Francisco in front of a crowd of more than 100 tech journalists. The new site design will launch today, but will roll out to users in stages.

Twitter currently has more than 145 million registered users and is experiencing phenomenal growth. At the beginning of the year, the company had 75 million users. That is still dwarfed by Facebook's more than 500 million users, but it is a significant user base.

A big part of what is driving Twitter's growth is the mobile space. "Twitter started on mobile. The whole reason for 140 characters was to fit on SMS, but we realized not enough people were getting the full Twitter experience on mobile," Williams said.

He said that is why the company started building its own applications, first for the iPhone, then for the iPad. And it is driving user adoption. Since the beginning of the year, Twitter users on mobile are up 250 percent, according to Williams.

Although by all accounts a banner news day for Twitter, the service did lose one of its most avid users. Despite amassing 3.7 million followers, pop music star John Mayer closed and deleted his Twitter account. He will be moving on to Tumblr, a much smaller micro-blogging service.

Tumblr, incidentally, also lets you embed pictures and videos directly into your news feed.