Quick answer to your question would be Yes. It is advisable to use Twitter. It helps in dissipating information quickly and to a fairly large set of audience. I would say twitter can be compared to a crowd where everyone has a mic and everyone is talking simultaneously. Some have larger mouthpieces and some have very small.
I am a fairly active user on twitter and still to come across a business where they use twitter. Some companies advertise about it but that is all. II havent seen it being adopted by a company per se.
For your research, I think you should talk to people @ techcrunch where they use it extensively to promote their posts. Guy Kawasaki used it to market alltop.com. A guy proposed his girlfriend for marriage on twitter. People use twitter but users are sporadic at best.
Also, I think we should look at the bigger picture beyond twitter. End of the day its about a platform where you can get the largest audience. These platforms have come and gone. It started with Internet, moved onto myspace, then facebook, now twitter. There would be another platform tomorrow (I have no clue what it would be but there sure would be one). We should be ready to harness these platforms rather than focusing exclusively on one single platform.
Hope this helps. Let me know if you want me to elaborate.
P.S.: Posted a link to my twitter page.
Thoughts on Twitter
Randy asked this question about Twitter on LinkedIn. Here is my answer.