Originally Posted by impulsoren
I'd be concerned on the part of the cheese, if it is naked to the air I wouldn't want yeast getting on it, that can ruin the cheese. Chances of the cheese bacteria getting to the sealed beer is unlikely though.
Depending on what kind of cheese you are making, yeast is not neccessarily a problem.
If you are making a schmear ripened/washed rind cheese (Gruyere, Fontina, Limburger, Muenster, etc...) then wild yeasts will probably take hold initially to raise the pH of the surface of the cheese so that the B. Linens can start growing.
If you are making a mold ripened cheese (Camembert, Brie, etc...) then there's a particular mold (geotrichum candida) that will do the same thing, raise the pH on the surface of the cheese so that Penecillium Candida/Camemberti can start growing. If you don't intentionally apply geotrichum, you could just get some wild yeasts to do the job. Wild strains similair to geotrichum are pretty ubiqitous.
Cave-aged cheeses are also similair. Wild molds & yeasts should be welcomed on the surface of the cheese. The more the merrier.
I don't think any of these yeasts are related to brewers yeast, however. I'm not sure what to tell you about cross-contamination. Personally, I would be a little concerned about lactic bacteria from the cheese infecting my brew, but if you are careful it hopefully would not be a problem. No promises though. I make both cheese and beer, and I keep them seperate, not for any sanitation reasons, but simply because they employ different equipment and require different enviroments.