Kiping,
I interviewed at Davis in early January and was surprised to get a decision 6 weeks later (I suspect my student interviewer really went to bat for me). If you get accepted, you will get a phone call from Terri Hall, followed by a large envelope (verrrry slow snail mail). Hang in there--in general, Davis seems to be quite slow at all stages of the application process (second-look weekend doesn't take place until May 10!). Believe me, I know from my other U.C. applications that waiting can be absolute torture...