Wikipedia says, "Steampunk is a sub genre of fantasy and speculative that came into prominence in the 1980s and early 1990s. The term denotes works set in an era or world where steam power is still widely used—usually the 19th century, and often set in Victorian era England—but with prominent elements of either science fiction or fantasy, such as fictional technological inventions like those found in the works of H. G. Wells and Jules Verne, or real technological developments like the computer occurring at an earlier date. "
Well, I guess we've all seen fantasy/sci-fi movies seem to take place in the past but with modern tools and fictional modes of transportation at hand. For example, here are some recent movies in the steampunk genre ... Sleepy Hollow, Wild Wild West, Hellboy 2: The Golden Army, Around the World in 80 Days, Sky Captain and the World of Tomorrow, The League of Extraordinary Gentlemen, Lemony Snicket, Van Helsing.
As I researched steampunk, I found there is a subculture of people who are really into it as a lifestyle with role playing, magazines, etc. It's sort of like how trekkies, renaissance faire lovers and S.C.A. members have their own little parallel world where just for a moment, they can be someone else living in a different time and place.
OK. So how does that translate to fashion, art and jewelry? Well, pretty interestingly actually. Gears, cogs, clock parts, Victorian lace, old leather bomber jackets, aviator goggles, monocles, antique brass filigree, corsets, computer parts, etc. are brought together to make things that are a mix of old and new with a semi-dark whimsy.
Here's an example of steampunk jewerly I saw on Etsy that got me interested in finding out what it was all about... See Mad Art Jewelry
Also see Mad Art Jewelry on flickr and check out 19 Moons on flickr too. (Note: The Winged necklace at the top of the page is by this artist)
There are many Etsy (and Ebay) sellers who specialize in the steampunk look too like COGnitive Creations, E.D.M. designs, Ruby Ann Designs, 19Moons, etc.
If you are interested in making some of your own steampunk jewerly, just search on 'steampunk' or cogs on Ebay. Also check Etsy Suppliers. Earthenwood Studio offers ceramic steamy stuff. Brass filigree seems to be a key component too and there are many sources. Vintaj is kind of pricey but they have aweseome stuff. Try Trinity Brass Co. Go to Search Etsy & Ebay Stores like B'Sue Boutique too. Ooo... And pretty blogs are all around for inspiration. Look at this post from Star of the East and Earthenwood Studios.
In the end, I don't think the steampunk look or lifestyle is for me personally, but it is visually interesting and so creative. I am in awe of the wearable art the featured designers have made.