iWeb has not been sold or supported by Apple for the past 2 years.
There are lots of alternatives around, but it depends on how complex you want to get. Yes there is Dreamweaver, but if you want something that is very like iWeb, then take a look at EverWeb at http://www.everwebapp.com. This is by Rage Software and is very like iWeb in design and use, but with all the things that we all wished that iWeb had.
If you want a Content Management System, then probably the better ones to use are either Drupal or Joomla rather than WordPress. Great for creating membership sights etc and there are many extensions, modules and plugins to extend functionality. If you know html and css, you can change the templates to suit what you want.
I have just transferred most of my sites to Drupal for increased flexibility and everything can be done online, so no more domain files.