Twitter is not a broadcast tool!
I was listening recently to Gordon White's Social Media Podcast - one where a panel were offering advice, hints and tips at a New Media Breakfast on: best use, the law, how to build a following and so on. A question that came from the floor by an inexperienced - but keen to learn - guy was something like "For a business I want to know the best platform to use, you all mention Twitter and Linkedin - I get Linkedin it appears to be a very professional network but Twitter seems very frivolous - What should I be doing?"
I'm not sure who responded from the panel but there was some waffle about both being great with a round up comment on Twitter saying that it was essentially a "Broadcast Tool!". The person that said this should be lined up and shot.
There are more uses for Twitter than I care to mention and hell, more blog space written on the subject than I care to list, however the best way to manage a brand and product is not through shouting, we're here, buy my stuff, aren't we brilliant... it is to listen and respond. For example Bank of America are gaining in popularity on the Twittersphere due to their help desk - they scan Twitter and offer advice, links to products when asked, conversations are taken offline to follow up in detail - essentially marketing the brand by offering help and advice.
I teach my clients that unless you are operating a "Fire Sale" stop broadcasting - listen and take part in the conversations relevant to your business and product - the best use of Twitter for a business is Customer Care - managing their expectations and pointing them in the right direction - not shouting buy buy buy!
Your business needs to set up search filters to monitor relevant conversations and join in.
Gordon if you're reading this look up "Social Media Podcast" in Google... I'm sure there's something you could do about that?