Parkside Diner, on Flatbush between Park and Sterling, was shut down by the DOH back in October, and never reopened. It was never anything special, but no-frills diners are becoming more and more scarce these days. About a month ago, however, work got underway in the space (and the awning was removed a couple days ago), and earlier today a tipster who'd spoke with the manager at the Kings Pharmacy next door let me know that it will be re-opening soon, possibly by the end of the week.
I had a chance to peek inside over the weekend, and the space has been completely renovated and cleaned up.
UPDATE: Many thanks to Sharon at the NFBID for filling in some of the details. Looks like it will indeed remain a Greek Diner, albeit with new ownership:
"The owner of the building is bringing in his own client, and ParkSide will be used as a diner with Greek owners. It will be a Greek diner and possibly serve along with the Hamburger Deluxe, some Greek goodies but it will not be a Greek Restaurant. The previous diner owners were booted for back rent and unpaid taxes."