The newest Version 5.0.1 (1547.4) of iCal, for Mac OSX Lion (Version 10.7.2), has the Sort Manually option for Reminders. As stated in the preceding reply, however, this option is not available in the iCloud Calendar. Therein lies the problem, apparently.
Yesterday, I was on the phone with Apple Support for an nearly two hours, trying to get to the bottom of this issue. Not knowing the answer, the first person I talked to referred me to someone in the iApps department. The person in the iApps department could not resolve the problem either. So, I was referred to a senior technician in that department. After a lengthy diagnosis, this person confirmed that this is a system-wide problem in which the function is missing. The case was forwarded to the engineers, and I will be notified when they have a response.
Once, I get the response, I will update this discussion thread.