After several earlier attempts to fix the problem, it looks as if Logitech's finally hit the jackpot. Version 7.3.3 of the firmware was made available earlier this week, and it's added major stability improvements to the Duet's wireless connectivity. We've tested it for the past several days, and haven't experienced a single dropped connection since installing it. The remote reconnected to the network every time, even when we left it off of the recharging cradle for hours or cycled the power (both of which tended to cause problems in the past).
Bottom line: This long overdue fix for the Duet looks like it's finally squashed an elusive bug that was hobbling an otherwise superb product for a large number of users. If you're a Squeezebox Duet owner, make sure to upgrade the firmware as soon as possible.
Current or former Duet owners are invited to share their thoughts--and any hands-on experience with the 7.3.3. firmware--below.