How do I import products?
There is no one solution for importing product data at this point. The most developed solution at this point is to use the Commerce Feeds module, which integrates with the Feeds module to import products in a variety of formats and created product displays for them. While there is no Commerce specific integration for the Migrate module, it is another project to watch as a possible solution.
When importing products to Drupal Commerce, it's important to remember that you have to import both the product definition and then connect that product to a display node (or some other display) for sale. See How do I display products for sale? for more information on why you have to do this. The good thing about the Commerce Product architecture is that once you have created a product display, you will not have to update it each time you update product data.
Users and developers interested in product import should keep an eye on the forums where import strategies are currently being discussed in this thread and others. We'll update this page as more information and contributed modules become available.