oh man, don't even get me started on msn etiquette lol. my gripes are many:
gripe #1: people that are on "away" all day every day. they log on in the morning, go on "away" and stay on all day. like, what the crap?? i don't message those people anymore unless i have something REALLY important to say. i think most people do it so they can be selective of who they talk to which is just patently ridiculous.
gripe #2: i have a friend that occasionally messages me and says "hi"...and then disappears. he goes to get food or watch tv or something. so i get the feeling he wants to chat and i'll say "hey, what's up?" and then not hear anything from him for 20 minutes. it's REALLY annoying. i try not to talk to him anymore.
i allow about 5 minutes for someone to reply to me before i start to get anxious. i know personally it's not strange for me to have up to 5 conversations going at a time on msn, so sometimes i forget about one if it starts to slow down. instant message conversations are weird though, i dunno, i still think it's a good way to keep in touch with people though. on the other hand, if you think that you should be in an exclusive conversation with someone on msn...well that likely will not happen, use the phone.