How would you make it cross platform. Would it be better to take the time stamping function away from the database and have the scripts create and store the time stamp in an Integer on the database. That way there would be no need for conversion no matter what the database. So what is the benefit of the timestamp function beside having the database handle the function????

It's kind of a tough call. What I've tried to do in my experience is to stay away from functions specific to one particular database - like UNIX_TIMESTAMP in MySQL. But many people would argue that point, especially if you want to fully take advantage of all that a particular database has to offer. My preference is to stay database independent as much as possible - this makes migration to a different database, at some point in the future, less painful :-)