Plancast, a new service for sharing plans, allows users to broadcast their excursion intentions to the web. The idea is that while current location-based networks (foursquare, gowalla, loopt) help users share their current location with friends, Plancast provides a peek into the future activities of your social graph.

With Plancast, you simply create a basic profile (or use Twitter or Facebook connect), and start posting your plans. Currently you can follow others without sending a friend request, just like on Twitter. You can also share these plans with your friends on other social networks by allowing Plancast to post directly to Facebook or Twitter.

The layout and interface is dead simple. Just type in what you’re planning to do, where and when, and click “Share.”

From a business perspective, location-based networks show great promise because they open up very real promotional and advertising opportunities for brick-and-mortar businesses on the mobile web. Special promotions can be offered at just the right moment, drawing customers in the door as they’re walking by. Here is an example of Foursquare providing a kind of customer rewards program, via their ‘mayor offers.’

I am a big fan of Foursquare, but I have to admit that it has its limitations. For example, If I’m in San Jose, the knowledge that two of my friends are grabbing coffee in San Francisco right now is simply not as valuable as it would have been an hour or two prior. As a result, Foursquare sometimes feels like a list of things that I’m missing out on.

A term coined by Jeremiah Owyang, the “Intention Web” allows people to organize and coordinate more easily. While networks like Upcoming, and even Facebook’s ‘Events,’ allow users to schedule events, Plancast hopes to aim for more informal plans.

In a recent TechCrunch interview, Plancast Founder Mark Hendrickson revealed that they have plans to incorporate a gaming system similar to Foursquare. He says they are also planning on making an iPhone application. These are really the minimum for Plancast to gain the traction it will need to succeed.

I think Plancast is on to something big, but they will need to better incorporate their service with others, and release a mobile application to gain real traction.