Budget - around $2000
Portability - IMPORTANT
Currently using a 13 inch, with a 23 inch external monitor.
With $2000 limit I can max out an air or get a basic rMBP. I also am eligible for an eduction discount.
You're shooting weddings. This means cameras, flashes, computers, cf cards, possibly strobes with stands, grips, brackets, backup body, different lenses, etc. No one in this thread has given a response with any thought put into it, and you aren't helping, as you haven't given any indication of what makes your current machine inadequate. Without knowing that, how does anyone know what to suggest? If the 2010 is a 15" i7, the Air will be around the same speed, maybe a bit faster on the maxed one. The maxed Air is still less powerful than the base rMBP by a fair margin if you're processing out a bunch of images on the fly. I have no idea if you're downloading to the internal drive, or whether you're doing this on location. If you're mass processing images later, the rMBP will finish faster. In terms of color reproduction and viewing angles, the Air's display is pretty bad. The rMBP is decent in that regard. It's not perfect. It's decent. It's exceptional for a notebook, and possibly better than a number of budget desktop displays. The smoothness from the resolution is excellent, although some applications may not be "retina ready" as in they don't scale well. CS5 will never receive this. CS6 has it scheduled, but you'd need to upgrade to CS6 to maintain further upgrade eligibility anyway as Adobe cancelled the up to 3 versions back policy they used to have.
In terms of weight, you're sweating a little over a pound. It makes a difference if you apply the same thing to several pieces of gear. If you're talking about one piece on its own, it shouldn't be a big deal. If you're dealing with a 15" now, the rMBP is still more compact. You haven't given any indication what size you currently use, and you should have done so if you expected any kind of decent response as opposed to random commentary. In terms of the Air, I'm not sure the upgrades offer great returns. Typically I'd just suggest the Air to save money. If you're going to spend the same amount either way, I'd rarely suggest it.