I just wanted to point out (in case there was any confusion) that the corkage is only charged for bottles of wine brought
to dinner - you can bring as many bottles as you like onto the ship for free. We're certainly planning to bring a few bottles!
There are some conflicting reports about when the corkage is charged at dinner. You'll almost certainly be charged for an unopened bottle (but not always!), but other cruisers have indicated that when they showed with a bottle already opened, most of the time they weren't charged. And no one has reported being charged for bringing a glass of wine to dinner.
The corkage fee covers washing the glassware you'll be using, occasional breakage (we're talking over time, here), and the extra time the servers will spend serving your wine. But really, it's a fee to cover the money they lose when you don't buy a (marked-up) bottle of wine from their list.
Based on the wine lists we've seen from the Magic and Wonder, you'd only save about $5 for the less expensive wines on the list by bringing your own bottle, factoring in the corkage fee, so that's your call. But for the more expensive bottles, it's almost certainly worth bringing your own.
The list is pretty good, although they don't include vintages (grr). Here's a version online to check out pre-cruise:
Disney wine list.
This was probably more info than you were looking for, but oh well! Have a great cruise!
April