If you need to build several sites with iLife’s iWeb application from Apple then Multisite is for you.
Whether you need to build 2 or 200 sites Multisite makes iWeb even better. It keeps iWeb uncluttered by focusing it on just the site you want to work with. It also speeds up iWeb since iWeb no longer keeps every site in the same data file. This way, when you edit or publish, iWeb works on just the site you want rather than every site each time. This helps to reduce memory usage and improve load and save times too.
To find out more about the features in Multisite see the press release.