Sort RSS feed events by date by adding a publish date parameter to the RSS feed url.  The publish date or &pdate parameter is useful when sorting in an RSS reader or when using a RSS widget now offered by many content management systems.  You will most likely want the &pdate value to be set to &pdate=o but here is the complete list of the values that can be used:

&pdate=o Event occurrence date (i.e. the start date of the event)
&pdate=c Event creation date
&pdate=e Event edit date (i.e. date event was last modified)
&pdate=n No date (i.e. do not include a pubDate tag in the event item output)
&pdate=f    Event end time

&pdatetz=1 Adjust PubDate timestamp for calendar's set timezone.

Here is a sample RSS link containing the &pdate paramater: Events&cat=all&pdate=o

Be sure to insert your unique calendar identifier into the link where it says "yourcalendaridentifier"

More information:
You may adjust other parameters in the RSS url to meet your needs:

&days=14 (controls # of days ahead to retrieve events - adjust as necessary)
&events=200 (controls max number of event to retrieve- adjust as necessary)
&cat=all (controls which categories included in feed - "all" may be substituted by a single category id #)
&pdate=o  (adds a publication date to the feed and is necessary to get the feed working in RSS Graffiti and other CMS website RSS widgets)