Yes (with development). There are several different ways to do something like this. One would be to automatically add people to a city group when they join (someone from London would automatically be added to the London group). You then would have to build a page that pulls in all content from users that belong to a particular group.

can you tell me the other ways if possible?

Im not a developer myself but my web guy isnt familiar with elgg and he is finding this paticular part hard.

I wouldn't think this is trivial so someone new to Elgg should struggle with this. Have you taken a look at the activity plugin that comes with Elgg 1.5? (It is only available from svn right now.)

Another possibility would be to automatically add people to friend collections based on location.

You should be able to get a list of users associated with the tag "London". From that you should be able to get the latest content created by those users. The activity and river plugins are ones you'll want to understand thoroughly.

Ok, i will pass this info across to my web guy

Thank you for your help and advice

sorry, what's svn? where do i get the plugin?

Your web guy should understand what I mean by getting it from svn. If he doesn't, you need to get a different web guy.

lol, ok thanks