I've worked on distributed teams that had an always-on video conference that everyone joined all day, every day. This facilitated much of the communication you

I've worked on distributed teams that had an always-on video conference that everyone joined all day, every day. This facilitated much of the communication you are describing. The team still used instant message and email, but if someone needed to have a conversation, it was just a matter of looking at them to see if they looked they were busy and just saying "Hey!" If other people were interested they would listen in. If they had something to add, it was just a matter of speaking up.