Silkeners are indeed chemical. It's basically nothing more than a relaxer/texurizer (sodium hydroxide or calcium hydroxide) but some oil and/or conditioner is added to it to slow the straightening process and it's left on for a short period of time. It's a way to loosen the kink or curl to the hair without it going completely straight.

It's nothing new.. people have done it for YEARS. People like Miss Jessie's and others have just found a new way to market it to natural kinkies and curlies that want that "natural look" but want a looser texture to their kinks and curls.

A lot of people find using a silkener/relaxer/texturizer is a way to make the hair more managable because it decreases frizz and makes the hair easier to comb. The only thing about it is the hair becomes porous, you have to make sure you have a good protein and moisture balance to prevent breakage, and you have to maintain it on some level because when the roots grow in that hair will be different than the rest of the hair. You really have to know what you are doing to keep your hair in optimal condition.

This is why a lot of naturals avoid these sorts of chemical treatments but they can work out just fine for people that know how to properly maintain the hair after the treatment is done.