Originally Posted by dteowner 
True enough, but the point is that if I see Peter on line with anybody but Policus, it's pointless for me to even bother him. Sure, everyone will be fluid, but it at least gives everyone a general idea of who they can group with.
You can easily send me a guild message and then I can swap to my level 7 cleric. I did that yesterday when Azraelck was playing with his level 5 character. He changed to his level 9 paladin and the both of us (my level 10 paladin) did several quests together.
So don't think that just because people are online with one character it means they can only play with that one. Sometimes I'm in a group and then I say so, but often I'm just online selling items, reorganizing my characters and looking for guildies to play with.