Tagging 2.0

I've been using tagging for quite a long time now (well, who hasn't?) and, though it's extremely useful, something is still missing. The missing thing is the context. Words without proper context can be interpreted really badly. Here's an example...

Let's say I have a program which stores all my photos along with their tags. I also have 2 friends: A and B. I just got a picture of A from B and picture of B from A. I add it to my collection tagging both pictures with A and B (I want to keep track of who is on the picture and where I got it from). Now how do I say I want to see all pictures I've received from B? I can't.

Now, my friend A really loves to send me photos and she does that a lot. About a month ago she sent me a photo of her dog. Is there a way I can easily find that picture? Again: no.

So here's my idea. Simple, yet powerful: let's add namespaces to tags! I imagine we could prefix tag with namespace name and a colon, so that we would get tags like person:a and person:b. I could also tag photos with from:a and from:b to keep track of who sent me the files.

Now when a user specifies tags he wants to search for, he can either type "a" to see all photos tagged with "a" in any namespace or specify, say, "from:a" to search for photos from user "a". I would also be able to search for photos of my friend A sent to me by my friend B by just typing "a from:b". Isn't that awesome?

The second issue (the one with finding files from a month before) can be also easily solved. It doesn't have much to do with tags, as it should operate on file timestamps, but it's a nice addition to tag searching. Basically I'd like to be able to specify time in my search. So I can do something like "a from:b 1 month ago". Of course it's possible that I got the photo 1 month and 1 day ago. My ideal program should find all the photos that match specified tags and then sort them by distance to specified time. So a picture from 33 days ago would be higher in the results than a picture from 15 days ago.

I know I'm not making revolutionary changes here, but I think that namespacing and time-aware searches would help usability *a lot* in many places (especially those with large collection of files). It would be great to be able to type "place:tokyo 1 year ago" on flickr and get exactly what you're looking for.

What do you think? Would you find this feature useful? Is there anything else that could be improved in tags?