How designers and engineers can play nice is a really great post by Jenna Bilotta. I nodded along enthusiastically to this point in particular:

Too often I observe my fellow designers rip into the aesthetics or interaction design of an early engineering prototype. When an engineer is met with critical feedback from a designer about issues they haven’t even begun to think about, it doesn’t encourage that engineer to include the designer in future reviews. This is how designers end up begging for massive changes the week before launch, and how we almost never get them.

One of the most difficult skills for a designer to learn is restraint during the early stages of implementation, when things aren’t perfect yet.

There are some great suggestions in the article – well worth reading.