Valve is providing Debian and Ubuntu developers with keys for its entire past and future library of games, and it seems that some people have tried to take advantage of this and get some Steam keys for themselves.
The distribution of Steam keys to the Debian and Ubuntu developers is being handled by a third-party company called Collabora, which is consulting Valve in open source matters.
One of the Collabora employees, who is actually responsible for sending the keys and verifying the authenticity of the developers, has posted a very interesting blog message, detailing some of the techniques and emails from various scammers.
So far, Collabora has distributed about 280 keys and there are about 1,200 Debian developers. Out of that pool, only seven emails have been scamming attempts, but the PGP (pretty good privacy) system used has been very helpful in filtering them.
Some of the scammers have been rather crude in their attempt, with the exception of one, who almost managed to impersonate a Debian developer.
Now that the offer has been extended to Ubuntu developers, more shady people are bound to show up for Steam keys they have no right in claiming.