In addition to what you have said in http://news.ycombinator.com/item?id=828692, I think that such teams (with slight conflict in interest) should be informed explicitly about each other being in the same market space.

Reason being, to put a word of caution in the otherwise too much friendly disclosures amongst the teams working in the friendly and healthy YC environment.

After this word of caution it will be completely upto the teams to do what they think is in their best interest.

What do you think? Should this be done as an additional practice? or does it sounds like way too paranoiac? Will it effect the environment negatively?

Thanks PG.