These tiny yellow dots with black bottoms are Cross Orb Weaver (Araneus diadematus) spiderlings.
I took this photo of an adult weaver spider in August 2009 in the same location where the babies were found so perhaps this is a relative (mom?). The females lay their yellow cocoons filled with eggs (up to 900!) in September, so these spiderlings may very well be hers.
After last week's soaking rain, the spiderlings had dispersed, but a day later I found them gathered together in a new location. They had taken up residence in the plant hanger attached to the porch railing. I found their drive to cluster together very endearing. Some of the babies had woven silky runners between the hanger and nearby bushes and were venturing out on their own. Within a couple of days, they had all gone their separate ways.