I seem to be being asked this a lot, so I thought I would pop up my simple answer:

FrontPage has been both extended and then split into two products.  We now have SharePoint Designer which is one child of FrontPage, but obviously ideally suited to modifying SharePoint (and OfficeLive) sites and then we have the “any type of web page editor” which is Expression Web.

If you look at http://www.microsoft.com/products/expression/en/web_designer/fpwd_faq.mspx you will also see:

How is Expression Web different from Microsoft Office FrontPage 2003?

Expression Web builds on Microsoft Office FrontPage® 2003 technologies to provide an unprecedented level of support for creating standards-based Web sites. Valuable feedback from customers like you have helped us create a new product that fully supports Web standards such as Extensible Hypertext Markup Language (XHTML), cascading style sheets (CSS), and Extensible Markup Language (XML).

If you are familiar with FrontPage, then you will find Expression Web easy to use. Expression Web has strong CSS support and takes full advantage of the power of ASP.NET 2.0 with integrated support for server and user controls.

Who is Expression Web for?

Expression Web is designed for creative professionals. However, experienced WYSIWYG Web designers will also appreciate the extensive features of Expression Web. No technical background is required to start using Expression Web. Convenient task panes and menus help users build attractive and compelling Web pages without knowing any markup or server code.

How is Expression Web different from Microsoft Office SharePoint Designer 2007?

Microsoft Office SharePoint® Designer 2007puts the emphasis on creating and customizing SharePoint Web sites. Expression Web is a new product for creating standards-based Web sites. The two products share common technologies including a high-fidelity design surface with deep support for CSS and ASP.NET.

Can I use Expression Web to work on files created in FrontPage?

Yes. You can use Expression Web to open Web sites created in any version of FrontPage and edit existing page content. However, one of the objectives of Expression Web is to help you create high-quality Web sites based on today's standards and technologies such as Web Bots which have now been superseded by ASP.NET controls with the same or similar functionality; therefore, you will not be able to add new page elements of this type. We are planning on providing a range of resources to assist FrontPage users with migrating their legacy sites to fully conform to these new standards.

Information on SharePoint Designer can be found at http://office.microsoft.com/en-gb/sharepointdesigner/FX100487631033.aspx

Information on Expression Web can be found at http://www.microsoft.com/expression (including a 60 day trial download)

ttfn

David