This is currently being looked at. When you purchase the beta in the Impulse store you get this message in the cart:
"This is a preorder item that must be purchased individually. No other items can be added to cart at this time. Please complete checkout, and your preorder will be saved in our system. You will not be charged until this product becomes available to you."
We are looking at making it bigger or contain a link for explination and so forth.
I too would liekto see an icon in Impulse indicating that I've made a pre-order. Maybe have it washed out and have the text on teh right indicate that it will be live at some later point.
What you need is what zubaz suggested here, and I suggested in the Impulse forum. The icon need to show up with text to the side:
Demigod: Preorder Beta
Awaiting Beta 2 Release Date for Availability
Something like this would be perfect. Also for my SINS preorder (before a beta was to be released), it should say:
Sins of a Solar Empire: Entrenchment Preorder
Download Available on Release Date 11/18/08
That would clear up a ton of confusion.