http://www.dopplr.com/

I am finding it very user friendly.

I've been using it for about the last year or so and have found it easy to use, too. FWIW, I'm here.

One quirk I noticed while traveling in Southeast Asia and Australia: I put my travel dates in, but the status updates ("jackal is leaving Singapore today," "jackal arrived in Sydney," etc.) were delayed almost a whole day. My guess is the statuses update at midnight whatever time it is where the Dopplr servers are, whereas it would be a better design to do the updates at midnight in whatever the actual destination time zone is.

Still fun and useful to announce where you are and where you're headed: I haven't run into anyone I know yet (I only have a couple people linked on Dopplr itself), but I do have it set to post my travels to Facebook (and keep all my friends there apprised of my jet-setting! )...

I'm afraid my trips are quite boring these days, but my family still finds dopplr the easiest way to keep track of where I am. Sure beats the long typed itineraries I used to email to them.

Hoping to draw some cross-global lines later this year

I prefer to use Trip It - http://www.tripit.com

I use both, but am friends with the folks who run Dopplr. Personally Tripit is more like the mile tracking / flight focused tool that will appeal to the FT crowd. Dopplr is more about finding friends who have overlapping schedules, knowing what your friends like in a new city, etc...

Trippit is much more focused on your flight, your tickets, miles, etc... Personally i get more out of dopplr, but your mileage may vary.

-rabble