[visualops]

If you want to remove the binder and sinter the metal, yes. But it is not required for a finished product. Some comments indicate for some purposes (likely artistic/decorative), it is preferred as is, just polished.
http://www.thevirtualfoundry.com/how-it-works/

[Cboldt]

Thanks for that - I stand corrected, sintering IS required to remove the binder.

Judging from the look of the finished example part, I'm not impressed. Some massive gross porosity.