Plaxo today introduced Plaxo 3.0, a new release of its smart address book service.

Plaxo 3.0 is the first online address book and calendar to synchronise seamlessly between Microsoft, Google, Yahoo, AOL, Mac OSX, Thunderbird, and mobile phones.

The new version makes simple what had until now been impossible: it offers automatic synchronisation of your contacts and calendars without without cables, cradles, or complicated software set-up.

In real world terms this means that events you add into one calendar will get transferred across to all the calendar applications you've linked in, and you only need to update a contact once, and the new details will likewise be updated across all the sites and services you use.

So with Plaxo 3.0 you can get access to all of your contacts and calendars at work, at home, or on the road - and it's free.

Offering a wide range of access options, including: a new web interface; native client software for Windows and Mac OSX; there are now several mobile options, including a new WAP 2.0 version for mobile browsers, available at m.plaxo.com.

The applications is can sync with are extensive and include Google (starting with Calendar, with Gmail coming soon), Microsoft (Outlook, Outlook Express, Vista Mail, and Hotmail), Yahoo (Mail and Calendar), Mac OSX Sync Services (for Address Book, iCal, iPhone, and more) AOL (AIM), Mozilla Thunderbird and mobile phones.

Plaxo 3.0 also includes Plaxo Pulse, a new automated content sharing system, that works a bit like RSS feeds - as people you know post content online, it just shows up automatically in your Pulse tab, based on their sharing settings.

Initial feeds include Flickr photos, blogposts, Amazon.com Wish Lists, and Plaxo contact info changes.

See the link to Plaxo below for more info, or watch the YouTube demo video.