I should start by stating that I am not a Patent Attorney and you should always get legal advice from an actual Attorney. I'm just an Entrepreneur that does not want to pay Attorney fee's and does it all himself (with no legal background).

From my understanding, the recent change in the patent system (March '13) related to the 'First-to-file' modification, which generally means (assuming two inventors invent the same thing at the same time), the first to file will be granted the patent. This is a change from the first to invent approach, which basically meant whoever could prove they built it first was granted the patent. From my perspective, this just means that you have to take the paperwork aspect of patents a little more seriously, and integrate it into your process at an earlier stage.

I did not watch this presentation, so I'm not really sure what that IP lawyer was talking about. But it sounds like it has something to do with Prior Art. The generalized concept here is that putting information into the public domain makes it "known", which would then imply that it is no longer novel. This information would then become Prior Art, which in some cases could invalidate the invention from being patentable. The important thing to consider here is the documentation or record of who put the information into the public domain. If the inventor put the information into the public domain, then it would belong to the inventor, and thus considered a Publication instead of Prior Art. If someone else put the information into the public domain, then it would belong to whoever provided it, not the inventor, and thus counts as Prior Art against the inventor (and thus, not patentable by the inventor). There is a one-year grace period between the time that you disclose the information, and the time that your publication grace period expires. So my understanding from this is that it actually works in your favor to document your IP, as long as you document it properly, make sure you are recorded as the person documenting it, and you follow through within 1 year. In the example of saying it out loud in a room of people (aka co-working space), then I can understand how it might be difficult to validate and record who actually said what. When documented on paper (or what they call, a Printed Publication), then it would be much easier to validate and record who provided the information. To get more information on how to properly document IP in a Printed Publication, here are some guidelines [1]. Aside from the methods described there, you can also leverage something called a Statutory Invention Registration. This basically means you want to prevent the invention from ever being patented by anyone, so you describe the invention and officially record it with the USPTO, and then waive your right to patent it. You can read more about Statutory Invention Registration here [2].

Getting back to your question, if you are really concerned about someone stealing your IP, then read link [1] and use some of those methods to document your IP. You could also go through the process of actually filing an application. I don't think just running your code constitutes as public disclosure (unless you display it on a projector up on the wall or something). A good rule of thumb is to just be careful about what you share, and whom you share it with. If you feel that it needs to be disclosed, then disclose it properly and protect yourself.

[1] http://www.uspto.gov/web/offices/pac/mpep/s2128.html

[2] http://www.uspto.gov/web/offices/pac/mpep/s1101.html