I have the same problem. I updated the plugin yesterday (the files within the zip container have the date 15.1.2011) and it doesn’t work.
I used a text widget where the following code was inserted:
my_calendar_upcoming before=”0″ after=”10″ type=”event” category=”General” template=”› <b>{date}</b> – {title}”
This works if i revert to Version 1.6.3 of your plugin