In a BBC News item Write here, right now Mark Ward writes, quoting Matt Jones:
The warchalks are intended to let people know about the open nodes that many people are happy for others to share.
Jones said he did not think there was much danger that it would be taken over by anyone malicious to post notice of corporate networks that are not doing enough to protect themselves.
“If someone is chalking it up they are doing something quite beneficial to the network operators by saying I have spotted this. Then they can decide to secure it or instigate a free wireless type scenario.”
This is an item that makes the whole thing easier to grasp if it is all a bit new – as it was for me. I’d love this – hope there are these hotspots wherever I go!