Hyperlinks are a technique used in HTML - why do you need them rather than using any of the other controls Flex supplies? Its easy to style pretty much anything in Flex to look like a hyperlink.
If you really do need them, Flex's text controls offer some (very modest) support for HTML, so you can just use a text control. In Flex 3 this was via the htmlText property, this has changed wit hthe new Sprite controls.