Since I have updated to ggplot2 2.0.0, I cannot arrange charts propperly using gridExtra. The issue is that the faceted charts will get compressed while other will expand. T
This is ugly but if you're under a time pressure this hack will work (not generalizable and dependent upon plot window size). Basically make the top plot 2 columns with a blank plot on the right and guess at the widths.
grid.arrange(
grid.arrange(plot.iris, ggplot() + theme_minimal(),ncol=2, widths = c(.9, .1)),
plot.mpg,
ncol=1
)