It seems that content_profile and ubercart and using ?destination don't play well together. Here's what I'm trying to do:

Have someone click on the ubercart link like this:

/cart/add/e-p300_q1?destination=user/register

which works, and takes them to the user registration page. If they fill out the page, it registers them fine, but the profile doesn't get saved, and also it removes the product that was in their cart before they registered.

Is this known behavior? Is there any way around it?