How to find which websites a certain product belongs to?

Question

A product can be enabled in several Magento websites. How can I get a list of these websites based on a product SKU?

Obviously, there is no $product->getWebsites().

Looks like this information is in the table catalog_product_website, but I'd prefer solving this without direct SQL.

mysql> select * from catalog_product_website;
+------------+------------+
| product_id | website_id |
+------------+------------+
|          1 |          3 |
|          2 |          3 |
|          3 |          3 |
|          1 |          4 |
|          2 |          4 |