I'm following the main thread linked above and am very glad we don't plan to be there until January, when I hope this has settled down.
The new procedure was implemented on Feb. 27. As noted, very early on arrival day Disney places a $100 authorization (a hold, not a charge) on the CC on file, then each time your charges exceed $100 they place an additional $100 hold (i.e., if you spend a total of $175 on arrival day, you will then have a hold of $200 total on your card at the end of the day). You're welcome to go to the front desk and pay down the balance with gift cards or cash at any time, but any balance remaining is charged to your card on day 5, the total existing hold is reversed (credited), and a new $100 hold is placed. Different banks drop the holds at different times, sometimes up to a week after Disney drops it, so some people have ended up with double the amount of actual charges counting against their credit limits (e.g., they charged a total of $1200 to their CC so had $1200 in holds and then $1200 in charges put through, so their credit limit was reduced by $2400). Some have also received fraud alerts and had their CC accounts suspended due to the frequent holds being placed or frequent holds followed by credits as they paid down their balances with gift cards. New posts in the last few days report that on day 5, after Disney put through the actual charge their CC was disconnected from their MBs and the guests had to spend time at the front desk or with Guest Relations reconnecting their CC to their account or calling their bank to straighten it up and be able to use their CC again. One poster said they visited GR 5 times during a 9-night stay due to CC issues.
Not unexpectedly, many posters report using CC and gift cards at point of sale now rather than charging to MB, so that only the initial $100 hold is on their CC from the resort, and many report not doing online checkin at all or going to the front desk on arrival to remove charging privileges from their MB.