Twitter has a new section on their website offering information on how businesses are using twitter for marketing and customer service.
This Twitter & Social Media Marketing Guide includes recommended books, Twitter definitions, and case studies of businesses using Twitter for marketing:
When people working in the Empire State Building twittered that they were craving ice cream delivery, New York local chain Tasti D Lite was there to listen and meet their need. When electronics buyers look for good deals, the Dell Outlet Twitter account helps them save money with exclusive coupons. …

There are many ways to use Twitter to market your organization, business or services.
Twitter is commonly used as a quick and easy way to microblog in 140 characters or less about the goings-on of one’s personal life. More and more businesses and organizations, however, are coming up with creative ways to use Twitter for effective online and word of mouth marketing.
First and foremost, Twitter is an interactive publishing medium. To use Twitter well for marketing you have to write, write often and write strategically.
Here are some high-level steps you …

Some see social media tools such as Twitter as sophisticated marketing platforms reserved only for the Coca-cola and Proctor & Gamble’s of the world. For many small businesses with no marketing budget who are struggling to survive in a difficult economy, Twitter has become their sole marketing strategy.
Small business owners around the world are discovering the benefit of using Twitter to speak with customers just as they would in person. Small businesses often get half of their business from word of mouth, so Twitter acts as the perfect digital word …

Google Wave Marketing? Wait a Minute, What is Google Wave?
Coming late 2009, Google Wave is a mashup of communications tools provided by Google to make it easier for people to work and communicate online. (Read more about Google Wave)
 
What Could Google Wave Change for Internet Marketing and Social Media Marketers? 

Google Wave could further fragment online audiences and limit the number and growth of today’s large social networks.
Dave Coursey of PC World says “Google Wave as a mash-up of chat, e-mail, and document sharing, it’s really something else: Google Wave could be …

What is Google Wave?
Google Wave is a mash-up of online communications tools to make it easier for people to work and communicate online. It’s a web application and computing platform designed to bring together social networking, IM, email and wiki — all with a collaborative focus and all working in real time.
 The folks at Google describe Google Wave as:
 “a new model for communication and collaboration on the web,”
“what email would look like if it were invented today”. 
Dave Coursey of PC World says “Google Wave as a mash-up of chat, …

 Apple’s new speedier, feature-rich  iPhone 3GS will provide exciting new marketing opportunities for Internet marketers.

Rich Media: Faster downloads, greater memory and processing speed will enable increased use of rich media advertising to iPhone users. Since the new iPhone announcement in March, some agencies have already experienced a 20% increase in iPhone advertising inquiries.
Geo-targeted Ads: the new Safari browser will have location-based technology, allowing marketers to develop geo-targeted ads for iPhone users (assuming the user gives permission to the website to see his/her location). Marketers will be able to serve ads …

Six Strategic Uses of Twitter in Marketing & PR
Growing numbers of individuals, small businesses, corporations and non profit organizations are jumping onto the Twitter bandwagon. Those who will find the most success will take the time to consider how they can use Twitter to their strategic advantage. Here’s a few suggestions how to make the most of Twitter for your marketing & PR:
Marketing & Advertising
Follow customers & future potential customers. Integrate your online and offline marketing &
advertising messages with your Tweets. Provide links to promotions, microsites, videos,
advertisements.
Reputation Management
Follow experts, industry leaders, news …

Have you considered using coupons as part of your Twitter Marketing Strategy?
TwtQpon lets you create coupons for promoting your products or services and then post them in your Twitter feed as part of your. If you have products or services you want to promote to your Twitter followers, consider offering a small discount or incentive in the form of a coupon and take advantage of the viral / retweeting features of Twitter.  TwtQpon says: ” Enhance your social media marketing by offering discounted coupons to the Twitter-sphere!”
See a sample Twitter coupon …

WordTwit Wordpress Plugin
WordTwit is a Wordpress plugin that utilizes the Twitter API to automatically push a published post to your Twitter account as a tweet. It allows all your Twitter contacts to keep up to date with your blog postings. One cool feature of WordTwit is that you can assign your own shortened url instead of using tinyurl.com or bit.ly or others. This way you get to build your own brand instead of someone else’s. In our case TwitterMarketingAgency.com is way too long of a domain to use, so instead …

Bit.ly Eclipses TinyURL on Twitter
bit.ly allows users to shorten, share, and track links (URLs). Reducing the URL length makes sharing easier. bit.ly can be accessed through our website, bookmarklets and a robust and open API. bit.ly is also integrated into several popular third-party tools such as Tweetdeck. A more full list of third party tools can be found on the bit.ly blog. Unique user-level and aggregate links are created, allowing users to view complete, real-time traffic and referrer data, as well as location and metadata. Tracking stats are available after …