Yeah, I make it a point to find out what my guildmates are doing when we group, seeing what spells they cast for what situations, and devise stratagems to use them with my class. Finally, at levels 45-52 our group is getting really good at knowing everyone's roles.
It is actually really funny, now when I am in a group of random people I formed with the LFG channel in a city, I will tell them stuff like "Hey, you, Warlock. I need you to cast your Soul Stone on the person in the party who is capable of ressurection, so we ALL can come back alive, rather than just you... and I need you to go nuts collecting shards so you can hand us all Health Stones... oh, and use your curse of Recklessness to keep these guys from running away and grabbing more enemies." Then I will tell the Paladin which Aura to use to benefeit the entire party, instead of using an aura just for him and his mana, and I will dictate which enemy I will sap and who is to aggro which enemy off of me and such... makes battles go soooo much smoother.