Do you have iWork? It doesn't come with the machine free of charge. You must purchase it. You should check to see which version you have. If you have '09, there's a free update that adds some Lion-specific features. If you have '08, then your choice is either to buy '09 or just keep what you have.
iWork '11 (or whatever it'll be called) hasn't been announced yet, so it's anyone's guess as to when it'll be come - or even if it will be coming at all.
If you're satisfied with what you have, I suggest waiting for a little while to see what happens this fall before spending $60 on the complete iWork '09.