OK, I'm going out of order because I haven't done any new Things due to doing some traveling this summer, so I'm trying to at least get to the Things that may be most relevant.
Email: It's indispensible but can be a time waster for me because I receive about 100 per day from all over the world - some junk, some requiring action. I really rely on my email archives to keep track of project status and communications. I frequently attach files or links via email. Currently my reference questions are about 45% email, 40% phone, and 15% in person.
IM: I remember WAY back in college (1980's) using "phone" on the VAX system at St. Kate's! We would "finger" our friends to see if they were online and then type instant messages across campus. My tweenage daughter used AIM (AOL's instant messaging) for awhile but I had heard it was quite vulnerabe to hacking and viruses, so when we got one I turned it off. At school the kids used "gaggle" accounts and spent a lot of time chatting with friends until the school account expired. I do not think many people use IM here at work; we use email that way sometimes (back and forth) in which case I pick up the phone and have a conversation with the colleague. I'm not sure which IM service I will try; probably a universal one like Meebo or Ebuddy...
Text Messaging: My cell phone is pay-by-the-minute so I try not to use it much. I have sent and received a couple text messages just to try it out, but do not use it regularly. I don't see a need for it in my corporate library.