I think they've come and gone. I picked up a couple when Toys R Us blew them out a while back (at about $12.99+tax, I think), and did sell an extra on eBay for about $17. Only Duracell-branded charger worth having
Just got an iPhone 4, and the first app I purchased was Battery Doctor Pro, which keeps track of normal and "full" (deep) charge cycles, as well as total health (based on 400 total cycles->80% health).