First-mover advantage??

One more everyday management jargon this, the one that we almost hear atleast once in class. but then, i think it probably might remain only in mgt books, some yrs down the line. How about the biggest example that comes to my mind as of now - the G-Mail/G-Talk onslaught on Yahoo mail/messenger. Well, it all depends on ur offers to ur consumers today than the first-mover advantage.