Diplomacy: In GT09, the official client-based diplomacy (where you can ask for oficial treaties, interchange money/city/tech and stuff...) can be triggered ONLY with an embassy. As the 1st embassy between 2 players can only be estabilish with a diplomat (or spy), there's no way to have oficial diplomacy until one of the players discover Alphabet. [Note that trading cities is also disabled in GT09]
Still, a parallel "unoficial" diplomacy can go on, e.g. in private chat, in privee forums, or even by a Cold-War-style red telephone line, if you have one
This way you will not be able to exchange any "goods", of course.
Beware of abusing diplomacy: it could leak many details to enemies. Remember that diplomacy and intelligence are the two sides of the same coin; but the side you will always need, is the latter.