Hi nevos, sorry it is not available yet. Because this Plugin for Eclipse. You need to find archive from download eclipse . I am sure for correct version of Eclipse and it is using for Eclipse 3.2.x - I am sure this click. If you download it and install choose plugin or standard builder. I am not sure What do you wnat?
If you couldn't find Flex Builder Plugin for Eclipse than you need to find Google. if it doesn't get available of download than you need to use Flash Builder Editor or Flash Builder Plugin using Eclipse 3.5.x
Thanks