They seem to come and go. Last Friday late afternoon I booked DCA-ATL-MUC/FRA-JFK-DCA for 7/2-12 for $1876 in Z. Went back later that evening to book another for August but they were gone for any cities. Sound like they are back again, but not sure which cities -- since underattack didn't offer details.
Discussed a bit in this thread
http://www.flyertalk.com/forum/delta...t-dl-sale.html
Got me playing around again,
DCA-SVO. $7452 for 5 nights, $2905 6 to 10 nights, $2405 10 nights or more.
DCA-PRG. $7500 up to 5 days, $2688 6 to 10 nights, $2188 10 nights or more. Seems to apply for a bunch of European cities with places like BRU, FRA, IST coming up about $1800 for 10 nights.