Robert_Charlton - 6:24 am on Oct 8, 2013 (gmt 0)
In practical terms, does this translate as:
the element # was formerly treated as a meaningless punctuation mark in searches, and now it's treated as something with semantic meaning
lucy24 - In practical terms, I see that the # symbol or hash symbol by itself has now become more akin to a search operator, something suggesting an area of limited search... similar, say, to the site: operator, with no space in between the operator and the text.
The hashtag includes both the # symbol and the text that follows.
To think about it out loud... a "hashtag" becomes a "container" of sorts, a container of clustered references which include different attitudes and perspectives about whatever they refer to. They can be sorted out by naming conventions, time, topical relevance, user relationships, etc, which they also carry. Very quickly, this becomes semantic.
Phrasing it fuzzily... these clusters become a kind of fuzzy neighborhood of entities, and I'm certain that Google is using this hashtag search to refine its extraction of named entitities from hashtags. Google is using the same principle in certain kinds of geo-based search, image search, and the Knowledge Graph.
See various comments in this discussion...
Google's Knowledge Graph Demonstrated with 'Bacon Number'
Sep 14, 2012
I'm guessing Google is also beginning to use it in Hummingbird.