Standards for Web Site Forms

Suppose you are filling out a sign-up form on a web site such as a social networking site. After the usual short answer questions like your desired screen name, etc., the site also includes a 10-20 line text area where you can type a paragraph or two to describe yourself. In some of these cases web sites will have the TAB key cause the focus to jump to the next form element if you press it while typing (without entering spaces or a TAB in the text box). Other sites will allow the TAB key to enter spaces (or a TAB) in the text area and allow you to continue typing in the text box. Which would you prefer.