I was experimenting with the Wave Warp effect and could come close to the effect I was getting with the Mosaic effect, except that it takes too long to render the Wave Warp, so I managed to refine the Mosaic effect so it can be used with more types of images. I'll post the refined effects after the gallery is back up.
One thing about the Mosaic effect, it may give you a different look if you export to a smaller frame size. With one video that I exported to 320x240 WMV, it didn't look like there was any effect applied. To remedy it, first I had to export it to DV-AVI, then I exported the DV-AVI to 320x240 WMV.
Does that mean that Premiere Elements doesn't apply effects until after the frame has been scaled down to the output frame size? That could be important.