Here's a message from Vern Grubinger, the vegetable and berry specialist for University of Vermont Extension FYI - be on the outlook! Do not replant last years potatoes and pull all volunteer potato plants. Sorry to say that there have been 2 isolated confirmed reports of late blight in the Northeast, one in locally grown greenhouse tomato transplants in the Northwest region of Pennsylvania and the other in a southern MD high tunnel on tomatoes started from seed. It is not yet clear where the inoculum came from.
This is a reminder to be vigilant for the disease on tomato transplants and on potato tubers early in the season.
A good summary with many useful links is at UMass Extension: http://www.umassvegetable.org/LateBlightAlertforTomatoandPotato.html
Hopefully weather will stay mostly dry and hot as this will limit spread of the disease.