I found this
article in the economist about how people use communication devices interesting, because of the quote from the "User adoption Lab" at Swisscom: "Users are showing a growing preference for semi-synchronous writing over synchronous voice"
This is something that I personally agree with, I'd much rather talk with someone for hours on an IM client or using text, because I can multi-task. This probably leads to my individual conversations lacking in quality and responsiveness, but with text I can go back and review what was just said so I can pick things back up. There's no rewind for voice communication besides "what'd you just say?" and I always feel like I have to answer quicker when talking. When writing, I can take some time to think about my answer without people getting antsy.
I'd like to hear other people's comments about how they generally use phones/IM/email for different purposes.