Well at first this seems like an unusual request as I don't see other blog engines doing this. But the irony is that my first implementation of google maps was in a custom blog for one of my customers. It came up as a customer driven need so I implemented google maps in my customer's custom mojoportal blog and then later implemented it as its own feature.
So the answer is yes its possible, easy in fact, but wasn't really something I was planning to do. It would take adding a new field to the mp_Blogs table and implementing the changes in the different layers to consume it and update it. Once that is in place its very easy because I implemented a control for the map which can be databound in the blog. Usage of the control looks like this:
<goog:LocationMap ID="gmap" runat="server"
All that is required is data binding or assigning an addrerss to the Location property of the control. So it is very easy to use this control in other features. All the Google Map module does is assign those properties. I am planning at some point to implement the maps in the Events feature because it seems obvious that an event has a location. Out of curisosity, I'd be interested in hearing about your use case for a blog with per post maps as Location doesn't jump to mind as a property for a blog posts for most blogs I read. Though I can see one use case if you were reporting news with a blog and wanted to be able to show the location of the news story events. I'm just curious how you plan to use it as it helps me understand.
Maybe 2 hours to do the whole project with all the data layers. I will get to it at some point but I have a lot of things already planned that are of higher personal priority to me. However, if you are in a rush for this and would be willing to PayPal me for a couple of hours of labor to sponsor this feature I can make it a top priority and deliver it quickly.