Great post! Yes, twitter is great for when we're travelling. I'm now using www.easytweets.com which means you can schedule future events before leaving for your business trip.
I haven't explored Dopplr but I've read great stuff about it.
So greatful I came across your post I absolutely agree and will use your post as an example of how to use some of the social media tools to connect to the right people. I've been invited to speak to uni students next month about preparing for the "real world" and how to use web 2.O tools to help them.
We talk to PR and Marketers here in NZ about social media. Early days for us here. So I was very happy to find a PR/Marketing blog about this subject. I've included your post in my blog this week.