Seesmic have just released the preview version of Seesmic Web for Twitter. A web-based version of their hugely popular Seesmic Desktop desktop app, Seesmic Web also has some pretty cool new features not found on the desktop version. The first (and really useful) difference is the threaded conversation option for direct messages. Now you don’t have to worry about trying to remember what you said to someone previously – it’s all there for you. The next option is a rollover…