just develop a HTML page, with a simple stylesheet. Thast all you need to do for developing mobile phone websites as i do it often.
I've done it in the past with developing html in simple form, but a plugin would go beyond that I would imagine handling special link tags that only work from a mobile phone e.g. within an imode setup.
I don't know of any plugin either... A good resource for beginners, or those who want their site to function somewhat on a mobile phone quickly, you can use this method: http://www.mikeindustries.com/blog/archive/2005/07/make-your-site-mobile-friendly I do what is described above to all of my clients sites.
I couldn't find anything for dreamweaver when I was looking about 4 months ago.. But Adobe GoLive CS2 has built in support for a bunch of mobile standards and mobile website development.. You might want to check that out..
Thanks Pixel Concepts I've already checked that out. Still interested in something that would work with DW though.