FrontPage has mercifully been discontinued and the new kid in town still in Community Technology Preview mode is the exciting Expression Web Designer.
Sparkle was an earlier code name and you can still view the concept videos on Channel9. Now a new website has everything you need to learn about all three of these new Tools.
Microsoft Expression takes the many sides of your creative personality to all new levels. Professional design tools give you greater flexibility to create sophisticated applications and content. Innovative technologies enable faster and richer interface development for Microsoft Windows applications or the Web. Compatibility between products increases all levels of your personal productivity.
Check-out the Tours and Demos and download the three CTP's.