Peeking at the code? Seriously...there are an insignificant number of software applications where code is the true IP.

Coding is never holy grail...it is a combination of the initial idea and the (often more importantly) the implementation of that idea that make or break a company.

No business that creates an application within the currently published infrastructure of Google Apps Engine is going to have enough rocket science in it to worry about having it stolen by Google (or any competent set of developers).