By now everyone in the known world is aware that Twitter had a two-hour outage this morning. Marketplace tweets, as does the Whiteboard, but when Twitter went down today, we all had to resort to our Facebook pages to let our legions of followers know what we're up to.

Joking aside, the denial of service attack was a serious blow to Twitter, which is, after all, supposed to be glitch-free and simple to use. Delaying the instant gratification that Twitter represents could send tweeters flocking back to SMS or even (horror) e-mail. PC World says this is bad news for those companies that have decided to use Twitter as a marketing tool, and have pumped serious money into trying to make it work.

Twitter has evolved quickly into a tool that companies rely on. It is a marketing tool. It is a public relations tool. It allows the company to engage with customers and partners in real time. While it hasn't quite achieved the status of a mission-critical application just yet, many companies are discovering Twitter as a valuable asset in their sales and marketing efforts.

Of course, PCWorld also poses the salient question: does it really matter? You can tweet us with a response!

Follow Paddy Hirsch at @paddyhirsch