I'm a newbie Tweeter. I joined up in May and I still feel like I'm new to the whole Twitter party. And I definitely think Twitter can be a major time waster, like anything else online.
HOWEVER.
Here's why I think Twitter can actually be pretty awesome for writers:
1. You meet and interact with a whole new set of writers. I've met a ton of great writers through blogging, but there are even more in the Twitterverse. Some just want to spam you with mentions of their book every two seconds, but others are in the same boat you are: querying, writing, on sub, revising, whatever. It's always nice to hear of other people who are going through the exact same things you are.
2. You can interact with authors. This is one of the coolest things ever. I've had tweets back from Myra McEntire (author of Hourglass and Timepiece), Simone Elkeles (author of the Perfect Chemistry trilogy), Miranda Kenneally (author of Catching Jordan), and Julie Kagawa (author of The Immortal Rules and The Iron Fey books). And those are just the ones I can remember right now. Yes, it's usually just a, "thanks for reading," or "I'm glad you enjoyed the book," but STILL. It's AWESOME. It's like being tweeted back by somebody famous. I get all fangirly and have to restrain myself from tweeting back, I LOVE YOU, YOU ARE AWESOME, I LOVE YOU!!!
3. You can interact with agents. Oh yes, the Gods of the Twitterverse (to us writers, anyway). The ones you want to tweet but you don't want to seem stalkerish, or suck-uppy, or idiotic. It gives you an inside view on what they like and don't like, and what they're like as a person. Sometimes they tweet about how busy they are, or that they've gone through their slush pile, or that they're loving an MS, so if you've queried them... well, let's be honest, it kinda just makes you all twitchy, but it still helps to know if they're busy or at a conference and so probably haven't gotten around to your query or MS yet.
4. Regularly on twitter are different chats, like kidlitchat, yalitchat, chicklitchat. Agents also hold "ask agent" sessions where you can get an answer straight from an agents mouth (or, er, keyboard). You also hear about contests, pitch sessions, cover reveals, book release dates, etc. And agents and editors often post tips on writing and querying.
5. *lowers voice to whisper* There are rumors, Twitter legends if you will, of agents actually requesting manuscripts from writers based on something they've seen on Twitter. Not just from Twitter pitches either. This hasn't happened to me, but I've heard that it's true...
I write this post because I, myself balked at joining Twitter. I really only did it because of The Writers Voice competition. But since then, I've learned the value of being a writer on Twitter. If you haven't joined, think about it.