Baidu Hi, be the first to experience it! - Participate in the Baidu Hi抢先体验 activity. (Note: "抢先体验" can also be translated as "early experience" or "prior experience" depending on context. Here, I've used "be the first to experience it" to convey the sense of urgency and exclusivity.) A more polished translation could be: "Baidu Hi, experience it first! - Join the Baidu Hi Early Experience Event."

This morning I found that the official homepage of Baidu Hi, http://im.baidu.com/, had been updated. There is a link to apply for experience on the page. After clicking and filling in the application form, you need to wait for the invitation notice.

Official Explanation:

Welcome to participate in the pre-experience activity of Baidu Hi. You can fill in the application here. After the application is approved, we will invite you to try out the experience version of Baidu Hi at the first time!

At that time, we look forward to your valuable feedback. And for users who provide valuable feedback, we will present a nice small gift.