We’ve talked about Seesmic before, we even saw a brief video demonstration, but this preview blows that away. Seesmic is looking like an excellent Twitter app for WP7, fully featured in every way imaginable, and it gels with the Metro UI perfectly. It integrates with both Twitter and Facebook, offers searches, customizable interface, geolocations, the whole shebang.
Color us very interested, especially as WP7 doesn’t look like it has native Twitter support at present (despite seamlessly connecting with Facebook). (They do now)