I used to read on my laptop, among other things, and listen to a lot of music on my iPhone. Since the ipad came along I've started distributing my tasks differently. When i want to just read or lurk, I whip out my iPad. I have also stopped carrying my computer with me to use when i am lying down. My laptop just sits at my desk now.
If I'm going to be doing a lot of typing, including IM'ing, I use my Mac. I am not entirely used to the iPad keyboard just yet and the auto correct bugs me to no end. I don't have the luxury of looking away while I type because some word might get replaced with something I didn't enter in the first place. I can do this on my Mac just fine.
My poor phone is only used when I go out or want to text someone.