Day one of TC50 introduced the first batch of the 52 best and brightest start-ups being showcased over three days in San Francisco, CA. Monday’s sessions focused on youth and entertainment, memes and news, enterprise, and advertising and commerce themes. Ashton Kutcher added celebrity buzz to the conference when he presented his social-networking and celebrity news site that targets tweeners, BlahGirls, during the first session. Not shy of a crowd, Kutcher later strolled through the demo floor with TechCrunch co-founder Jason Calacanis’ bulldogs, Taurus and Fondue, while fielding questions from the press. Marissa Mayer, the VP of search products and user experience at Google announced Google News and Archives, a feature allowing Internet users to search for old newspaper articles and view them in actual news print form via a

PC. In honor of Google’s 10-year anniversary, birthday cupcakes were presented to Mayer on stage while TechCrunch founder, Michael Arrington, tried and failed to rouse the audience in a Happy Birthday sing-along.

Panelists, which included tech investors, software engineers, and social networking experts, played nice in the early part of the day with few criticisms. However, by the third enterprise theme session, panelists Yossi Vardi and Marc Benioff brought some lively banter to center stage by goading one another. Joint-panelist Marc Andreeson followed the light-hearted, jocular tone of the session by suggesting an American Idol-like set up where panelists remained on stage during the four presentations and gave feedback after each presentation, a move widely accepted by the audience.

Not all fun and games, the first day introduced exciting new technology. Yammer, a tool that allows companies to benefit from interoffice twittering, and OpenTrace, a Web infrastructure that traces the environmental impact of any purchase, both received praise and applause from panelists and the audience.

Wi-Fi access was less than zero at the event Monday, which left many attendees and press members beyond frustrated. In an email late Monday night, Calacanis promised the availability of extra ethernet cables for the remaining two days of the conference in conjunction with fixing the Wi-Fi problem.