As your order moves through our system, it'll generate status messages. Here's what they mean:

Pending Review
You'll get an initial message that your order has been added to our production queue.
Queued for Fabrication
Your PCB design is A-OK, and it's getting ready to be submitted to the PCB fabricator.
In Fabrication    
The PCBs for your order are being made. At this point, no amendments that change the PCB design will be accepted.
Queued for Manufacturing
Your order is waiting for it's turn on our equipment. At this point, no amendments of any kind will be accepted.
In Manufacturing
We're making your stuff. Note that this phase of things may be short, or it may be a few days - we're doing a few different things, and they may not all happen one after the other.
Your stuff is out the door! We'll send you details like tracking number (if applicable), production notes (if applicable), etc.