This service is not new but I only came across it today. TripIt is a travel organiser that is aimed at making it as simple as possible to organise things related to your trip. Getting started couldn't be easier - all you need to do is email them your booking confirmation and it converts it into an itinerary.
I sent it my booking confirmation for my flight to San Francisco and in a few seconds had converted it and started my itinerary. Next I sent a confirmation for a hotel and it updated the itinerary and even created a Google Map with directions from SFO to the hotel.
TripIt will also throw in maps of the area you are staying and will either give you accurate weather information or averages if you are not travelling within the next few days. There's also a simple travel guide for the area you are staying in and a facility to export the itinerary to a calendaring application.
Other features include the ability to bookmark site using a bookmarklet, a mobile version of the site and ability to get travel information emailed to you.
As with any new service, there are also social networking features included. I haven't tested these out but the aim of them is to connect you with either people who are travelling to the same destination as you or people who are travelling to where you live.
Rather than offering a searchable database of travellers who say have allowed their trips to be viewable, the social networking feature relies on searching your address books for people that you know who have registered with TripIt and shared their itineraries. As I haven't got a huge list of contacts, the option to find people I don't know who are travelling at the same time may have been of some use to me.
I did run into a few problems when using the site. It handled booking confirmations from Expedia with ease but when I added some from BmiBaby and Travelodge the site didn't recognise them even though they are listed as being supported. I'm sure this will change over time as more travel providers are supported.