Spam (noun) is commonly defined as an unsolicited commerical message sent indiscriminantly to mass recipients. Is this what HSBC is trialling in the name of marketing?

The initial message it is sending out to all activated phones near its branches is certainly unsolicited (though one could argue that if people leave their bluetooth turned on all the time they are just asking for it). But this message itself isn't a commerical message - instead it is a one-off invitation to accept the download of a marketing message. This permission aspect gives a company like HSBC something to fall back on in defending itself against spam claims, but my concern is that there was no opt-in for the initial email.

As one person interviewed by the Mail on Sunday said, "What if every store did this?". 

I have read about better implementations of bluetooth marketing that are a bit more targeted. What if HSBC's bluetooth server only targeted phones inside the branch? At least then, it would probably just be annoying customers that it already sends regular advertising to through the post.

An even less invasive implementation of the technology sees small bluetooth transmitters embedded in small areas of an advertising poster, which invites people to hold their phones close to the poster to recieve additional information, or download things like ringtones, video clips or images. 

This opt-in information transfer is also a use-case that mobile operators are considering for near-field communication (NFC) contactless chips that handset manufacturers are looking to introduce in their devices over the next few years. Because these handsets can act as a reader of relatively cheap passive tags (cheaper, I suspect, than a bluetooth transmitter), a user could, for example, wave their mobile phone in front of a tagged timetable at a bus stop to instantly download that information. Or, in a bank branch, they could be invited to wave their mobile phone in front of a poster advertising a new mortgage deal to download more information and an application form.

I think the key to the success of all these technologies is making the customer the actor and initiator of any information transfer, rather than someone who is bombarded with unsolicited messages that are more likely to annoy them than turn them into a potential customer.