There are two shows running currently that I am aware of. One is Not in Kansas Anymore: A Tribute to The Wizard of Oz at Nucleus, a gallery in Alhambra, CA. If you click on this link, you can visit their website and view the pieces that are on display and for sale.
Another exhibit called Visions of Oz: A Celebration of Art from Over the Rainbow is being held in Los Angeles, at the Heritage Square Museum. There doesn't seem to be an online gallery to view for this show, but a number of pieces from the exhibit are being run through eBay, by Creature Features. These can be seen by clicking on this link, and clicking the eBay auction link at the top of the web page.
I couldn't resist adding this small set of the four friends, as painted by artist Tony Lombardo, to my collection. They look like they stopped in at a photo booth while visiting the Emerald City!
These particular images were also used in the advertising for the show. Love those green glasses!