The demographics of the users will be like LinkedIn. We want the logo to be professional, but have a comfortable consumer-friendly look/feel. Apple is an example of a company that has brought consumer-aesthetics to the enterprise world and that is something we would aspire to convey.
I've found when putting together a mood board that I like the following: "square/rectangular with soft edges", "minimalist", "masculine but subtle colors", "denotes high performance", and "professional but not boring."
In many of the more recent designs I've seen outside of 99Designs, I've noticed a trend of professional fonts augmented by a simple design, typically in blues or grays. This design is often used as the proxy for a square "app" icon (e.g., found in your iPhone). If you can provide what a square "app" icon would look like in addition to the rectangle logo, that would be appreciated.
Thank you all!
Some more feedback (which I'll append to the design brief):
I really appreciate the submissions of the V as the square icon but each variation feels derivative of prior entries. So far, #53 is my personal favorite out of these type of logos/icons. That being said, I can't imagine that logo/icon looking that much better than what is. While I will not discourage any designers from continuing down this path, I can say that these designs have diminishing returns.
One thing to consider is to play with the idea of "stack." One thing I admire about the logos for Square, DropBox, and Simple are the iconic graphics that accompany their "clean, professional" fonts. These graphics can be deliberate (like DropBox's translucent box) or invoke a mood/image (like Square and Simple). If you want to experiment with the idea of stacked boxes, that may be something new to try.
Consider Amazon Web Services. I really don't like their stacked boxes but I admire what they're trying to convey. I'm sure there is a simpler and more truncated version of that theme, which I hope 99Designs' community can help me visualize.
Thanks again. Great submissions!