De acordo comesta excelente apresentação Ao projetar interfaces RESTful, a maneira preferida de implementar o controle de versão é utilizar o cabeçalho Accept, usando algo como:

GET /products HTTP/1.1
Host: example.com
Accept: application/vnd.com.myservice.v2+xml

Isso funciona perfeitamente para os tipos de conteúdo XML, masé possível usar o mesmo esquema para versionar o equivalente a JSON?

Ou seja, é possível pedir:

GET /products HTTP/1.1
Host: example.com
Accept: application/vnd.com.myservice.v2+json

A resposta seria algo como:

HTTP/1.1 200 OK
Content-Type: application/vnd.com.myservice.v2+xml; charset=UTF-8
Allow: GET, POST

<?xml version="1.0" encoding="utf-8"?>
<products xmlns="urn:com.example.products" 
          xmlns:xl="http://www.w3.org/1999/xlink">
  <product id="1234" xl:type="simple" 
           xl:href="http://example.com/products/1234">
    <name>Red Stapler</name>
    <price currency="EUR">3.14</price>
    <availability>false</availability>
  </product>
</products>

e o equivalente JSON (tipo de):

HTTP/1.1 200 OK
Content-Type: application/vnd.com.myservice.v2+json; charset=UTF-8
Allow: GET, POST

[
  {
    id: "1234",
    links: [
      {
        rel: "self",
        href: "http://example.com/products/1234"
      }
    ],
    name: "Red Stapler",
    price: {
      currency: "EUR",
      value: 3.14
    },
    availability: false
  }
]