We have a new word: modentity. Coined by Doc Searls to mean the combination of identity and location. I've been thinking on something like this myself for a while in combination with Jabber and my Jabber World Map.
What if you can combine your present location with your identity, so (selected) people can see where you are, or with your blogging activities (or moblogging). Or let's take it a bit further, and combine information about the surrounding objects at your presence location like this project by Matt Mankins called Location Linked Information.
That last one is a combination of the other two I guess. You can view information (nuggets) about your surroundings and annotate that information with your own comments. Think of having lunch at some restaurant and then write your quick comment about it, just then en there. Others who visit that neighbourhood can read your nugget. Businesses can write their own nuggets, for you to see if you wanted to.
Matt calls this hybrid of the virtual and real world glean space and thinks such a system will make people hyper-aware of our surroundings. An awareness we tend to lose in cities. Matt is working vividly on this project and envisions a system where all these nuggets are stored in a distributed manner. Using Jabber, it will have lots of Jabber servers all storing information about a small part of their (virtual) world.
I can't wait to test this out.