Airbnb was essentially always about being a marketplace to let home-owners earn some extra money by renting out a spare room or an entire property. But the model is slowly changing.
This evolution has seen apparent value-add things such as Wish Lists and the recent Neighbourhoods functionality (to learn more about what's going on in a particular area of a city), but there have not been any significant changes to the core proposition.
Perhaps until now.
About six months ago, just before its acquisition of LocalMind, Tnooz Node Daniele Beccari speculated how the Neighbourhoods functionality might develop - but it appears the first signs are now beginning to feature on the site.
Earlier this week a Tnooz reader alerted us to what they presumed was an error on the site, how a host was also selling day tours around Vietnam.
"Obviously their filter isn't catching this stuff," the reader wrote in an email.
Whilst this particular host also seems to using Airbnb for quite a lot of OTHER activity (reviews on the profile indicate she has captured some business for own online travel agency for hotel stays and activities in various destinations, for example), fundamentally the member is using the site to sell non-accommodation services.
Surely some mistake?
Airbnb inked a deal with activity provider Vayable in late-2011 so that users could receive ideas of things to do in a location via an email ahead of their visit.
But that's just CRM up-selling.
It turns out that that what was thought to be just a cheeky bit of opportunism on the part of the host in Vietnam, which had slipped through the net, is now permitted on the site.
This is a fundamental switch in the model at Airbnb: any host can effectively become a tour guide (and sell that as a service), either directly to an existing member staying at their home or, crucially, act as an intermediary to those providing activities in a destination, as in the case of the Vietnamese host.
An Airbnb official confirms it in an email:
"Since launch we have seen people use Airbnb in many different and unique ways.
"Whilst providing hosts a platform to rent out their spare space and travellers a way to book it remains our core offering, we don’t want to discourage anything that provides more meaningful trips and better travel experiences for our community."
Such a change in what Airbnb is now offering to members could send a slight shiver down the spine of the countless person-to-person marketplaces in travel experience which have sprung up over the past few years.
Why? Airbnb has volume. Lots of it.
If a tour provider wants to muscle in on that network of upwardly mobile Airbnb fans then, in theory, it simply has to register as a host on the site and start selling a few rooms and then its other products.
Alternatively, behind the scenes, it could partner with some of the existing hosts so that they can start "selling" product on their behalf.
But, similar to a number of issues which have clouded the Airbnb model throughout its history, could firstly be the prying eyes of regulators but also potential implications for consumer protection and liability.
Acting as intermediaries for a tour or running an activity themselves throws up all sorts of problems around insurance and responsibility on behalf of hosts.
Or, indeed, Airbnb itself.