Well, I’ve been using Twitter (somewhat irregularly I admit) for a couple of weeks (follow me - http://www.twitter.com/shlarsen) and wanted to share my first impressions.
Why use Twitter? 
First, Twitter is a good tool for product research and brand management. You can search through Twitter posts for mentions of your brand, products and services by using a Twitter search tool like Terraminds (http://www.terraminds.com/twitter/). Research shows that Twitter’s audience contains a large group of first movers in the internet and software markets. According to Quantcast (http://www.quantcast.com/twitter.com), Twitter “reaches approximately 43,830 U.S. monthly uniques. The site is popular among a more educated audience.The typical visitor reads Techcrunch.” If you have access to Forrester, check out Microblogging For Marketers. The analyst, Peter Kim, talks about the report in his own blog, “I just don’t get it.” [i.e. Twitter].
“Our data shows that 6% of US online adults use Twitter regularly.
If you want to reach an affluent, well educated, and early adopter audience, there might not be a better communication channel out there.”
This means you can get some early feedback regarding the good and bad features of a product or service and a sense of the sentiment of the toward them and your brand among this audience.
Second, Twitter is great for building your own personal brand. As implied in the Forrester report, you should think of Twitter as a micro-blog. It’s easy and quick to post and doesn’t require the research and editing of a full blog post. It provides an opportunity to post your thoughts, interesting links, and news that promote your brand. However, as ProBlogger points out in Why Twitter Isn’t a Waste of Time, “Twitter messages are archived and searchable. Forever. Remember that.” So it’s important to be consistent and professional with your Twitter posts.
How to use Twitter
First, create an account using your online username and upload your picture or avatar. For branding purposes, it’s important to use the same username (if possible) and picture throughout your online presence. This helps your fans to recognize you from site to site.
Second, find some experienced business Twitterers to follow. You can get started by checking your favorite bloggers to see if they are on Twitter. Follow the market research analysts or journalists that cover your space. Look through their archived Twitter posts and monitor their current activity. When you feel comfortable, start posting. Once or twice a day is fine, there’s no reason to post every five minutes about the minutia of your day. Look for interesting links, post your thoughts on the major news events of the day. Comment on the posts of the people you follow. The nice thing about Twitter is that you can dip in and out, missing hours of tweets without guilt. 
Third, install an application that lets you use Twitter away from Twitter.com. Using the native interface at Twitter.com for posting for for monitoring the people you’re following is a pain. There are several good tools for interacting with Twitter from your browser, phone and desktop that make the experience much easier. I found Twitter 4 Skype (http://k2works.sub.jp/twitter4skype/) too intrusive for the desktop, but it’s good for using Twitter from your smart phone. Having the Skype window constantly popping up with posts is just too distracting. Twitbin (http://www.twitbin.com/) is much easier to live with. Twitbin is a side bar for Firefox that displays the posts from the people you follow and includes a simple way to post directly to your own account. It can be turned on and off with a click of the mouse. I also like the Twitter widget for Netvibes (http://www.netvibes.com), but it doesn’t show as many posts at a time as Twitbin. I will devote a whole post to Netvibes in the near future - so more about that later.
Syndicating Twitter 
Once you’re posting regularly, you can syndicate your Twitter micro-blog. Start by installing the Twitter Facebook (http://www.facebook.com) application (if you don’t have a Facebook profile, make one!). This application includes the option to update your Facebook status with your Twitter posts, but micro-blog posts are generally not related to your “status” to I recommend not using that feature. Why post a link to an interesting blog post as your Facebook status? On a side note, I’d still like to find a tool for updating my Facebook status from outside Facebook, but Twitter is not it. There are also Twitter widgets for blogs and most of the other social media sites as well. You’re spending the time creating this new micro-blog - let people see it!
Further Reading
Newbie’s Guide to Twitter from Webware
A Guide to Twitter from WebProNews
10 things to do when you start using twitter.com
Twitter for Personal Branding from Marketing Pilgrim - check out the comments on the post.
Twitter-fan wiki - online help from Twitter users, but not an official Twitter site.
Web Strategy: What the Web Strategist should know about Twitter from Web Strategy by Jermiah provide a great overview.
Microblogging For Marketers from Forrester Research.
“I just don’t get it.” [i.e. Twitter] from Being Peter Kim, the Forrester analyst who wrote the previous report.
Why Twitter Isn’t a Waste of Time from ProBlogger
How to Write a KickAss Twitter Post from B.L. Ochman’s weblog