We ate there last Friday and it was my birthday. I made note of it when making the reservation and wore my birthday button and the hostess said happy birthday to me when we checked in.
I didn't mention it to my server and asked my family not too either as we'd been celebrating my birthday all week at WDW and quite honestly, I was birthday-ed out.
I didn't know if she noticed my button or saw it noted on our reservation, but nothing was done.
I'm sure if you make mention of it, they will do the typical cupcake and perhaps sing. If you want the special treatment, make sure they know about it. We made mention of it at Crystal Palace and CRT and both times they sang and gave me a birthday cupcake. Both places sprinkled Mickey confetti around our table too.
I also got a call from Goofy, a free dessert when getting a drink at Cosmic Ray's and balloons and a card from the staff at WL. Plus when wearing my birthday button, I got a LOT of "Happy Birthdays" from CM's and other guests. All very nice surprises!