For what little difference meta tags make, from my observation I would say order might make a slight difference. I have noticed a difference by putting the most relevant, important keyword first in just about anything, including keyword tags. Again, the tag itself may become obsolete in the future. But for consistency, I would still excersise the habit of putting your best keyword first anytime keywords are listed, whether it be title, content (close to the beginning), or when you have the option of adding keywords for directory submissions.