I have had several customers ask me lately about the .co domains and if they should get that since their company name was taken in the .com
For some it all depends on what they are looking for. The main problem that I see with this domain is that when someone reads the card or print material the reader will think that the printer made a mistake and left off the "m" at the end and the reader now ends up at the wrong site.
Now for IM it is probably not as much of an issue as it is a live business.
Are these going to go the way of the .info and .us? Not as much value to them.