Is Twitter a real marketing tool, or a time waster?

If you judge a marketing channel by reach and frequency then we may just have to have a discussion about Twitter. "What am I doing?" I'll tell you what I'm doing-- I'm trying to figure out if the reach is sufficient to justify any investment or planning to use Twitter in a digital marketing strategy. There's no cheating this one. It's not like email where you can spam 000's of people with your message and hope for a 'ok' conversion rate. Users of Twitter have already created a blacklist of people whose following-to-follower ratio is too high. So what then? Maybe it's just a good way to stay connected. A way to let your friends, family, colleagues and total strangers know what you're thinking, dreaming, txting, surfing, stumbling about... If I've got a product or service and I want to spread the word virally, then all I really need is a hard-core group of influencers-- a seeding group. If it's the right message, to the right target audience, then the right influencers can spread the word faster than a million poorly targeted emails. If you're in Canada, and work in marketing, advertising, media, loyalty or interactive: Follow Me and I'll follow you...UPDATE: Check out Andrei's post about using Twitter for special announcements.