I was finally able to sync up and find the CupKates truck in Berkeley. I tried S'mores, Twinkie, and Salted Caramel flavors (sharing with others). Purchased the Strawberry Swirl, Double Chocolate and Red Velvet too but did not get a taste of those.
The cupcakes are on the small size but very light and moist. The S'mores flavor was particularly fun with graham crackers on the bottom and a tasty marshmellow frosting. My favorite taste was the salted caramel. The frosting is a heavily whipped almost pudding-like buttercream without any grainy texture at all.
I'm looking forward to trying a few more flavors (especially the Guiness). The Twinkie flavor for me was not too exciting.