This style for Google Calendar adds some color to the "nonmonth" days in the multi-week/Month views in order to set them off from the current month's days in the view. (created by special request) You can easily edit the code to change the color to another one you might like better. The default background color is Google Calendar's darker blue (which matches the sidebar separator); the default font color is the even darker blue of the nav buttons (which you can also change to suit your preference--you may not want to see the nonmonth numbers at all).

Helpful hint #1: when using the little nav calendar to create a multi-week view, and you start dragging the mouse cursor down from the current week, if you're near the end of the month, then you may finish up with the cursor in the next month, and since the last day/week of your dragging action will become the current day[/week/month], this will reflect here--what you logically think of as the "current month" (as in, "now") will look like a "nonmonth". So, instead of dragging down from the current day/week, drag up to the current day/week; then, the current week will stay the current week. :D (That was clear, right?)

Updates...
03Jul2010: don't override Today even if it's in nonmonth