The events do have a creation date attribute, but it is not usually visible. To learn how to force its appearance, please see:

http://www.rememberthemilk.com/forums/ideas/2612/

I would really like to be able to sort by creation date, but that is not available so far.

I have found that using some of the added search terms helps with this. For instance, I can quickly locate all the tasks that are still active, but that I created before the beginning of this year.

These are the options listed in the advanced search table of operators:

added: Used to specify added date. added:today Tasks added today.
addedBefore: Used to specify added before date. addedBefore:1/1/2007 Tasks added before 2007.
addedAfter: Used to specify added after date. addedAfter:31/12/2006 Tasks added from the start of 2007.
addedWithin: Used to specify added within date. addedWithin:"3 months of today" Tasks added in the past 3 months.

For me, the biggest issue with the time and date stamp is that when edit a task on my Blackberry, the time and date stamps of all its notes are re-set to the time that the task next syncs with the RTM web site. So, for instance, if I noted that I had telephoned someone about something related to the task, I would have to manually add the date and time to my note, since there is a good chance that RTM will re-set its automatic stamp the next time I sync.

Time Stamps viewable in column - Yes please!
Search by date created - Double Yes please!