Two years ago, a handful of mysterious swings popped up around town, filling passersby with both nostalgic wonder and befuddlement. Now it looks like there's a new public art phenomenon aiming to tickle our collective inner children: whimsical mobiles.

Reader Josh K. spotted one such mobile in Duboce Park recently. Both the mobile and the utility pole from which it hangs have been adorned with large lego blocks. Josh sent in the following animated gif of the mobile in action: A second mobile hangs from a light pole on Octavia Street in Hayes Valley, featuring mirrored discs, yellow blocks, and multicolored rods: Yet another mobile hangs on Castro Street, in the alleyway next to the former home of the Naia gelato shop. That mobile features Ken dolls embracing each other in various states of undress, surrounded by rainbow flags: We're not sure who the artist is, nor whether these pieces are connected to each other at all. If you know, or if you've spotted other mobiles in the city, do tell...