I took a walk through Davis Square just now so you don't have to. Here's what I found open and closed:
Open - Flatbread,Mr Crepe (closed at 1pm), Johnny D's, Diesel Cafe, Dunkin Donuts, Rosebud, Anna's Tacqueria, CVS, Tedeschi's, McKinnon's (was open, now closed), Farmers' Bounty, ETA, 1:30 pm: Diva, Burren, Redbones, Mike's, Cristo's, Chipotle, Sligo, Family Dollar, Downtown Wine, ETA 4:30 pm Foundry (at least for dinner), Posto (ditto)
Closed - Blue Shirt Cafe, Starbucks, McDonalds, Gargoyles (sign said "disco brunch cancelled"), Buffalo Exchange (had sign on door), Goodwill (ditto), ETA, 1:30 pm: Namaskar,Foundry
Foundry, Diva, Namaskar, Burren all looked closed but I don't know if they would normally be open at 10 am anyway
Open - Flatbread,
Closed - Blue Shirt Cafe, Starbucks, McDonalds, Gargoyles (sign said "disco brunch cancelled"), Buffalo Exchange (had sign on door), Goodwill (ditto), ETA, 1:30 pm: Namaskar,