phranque - 3:05 pm on Jan 20, 2009 (gmt 0) i'm not sure this really does what you want.
there's an example in the w3c wcag doc which uses the ordered list for a sequential process:
H48: Using ol, ul and dl for lists ¦ Techniques for WCAG 2.0 [w3.org]
That definitely qualifies for an ordered list. The best thing is that you don't need to type the corresponding letter for every new item. Just style your <ol> to display them automatically
an alphabetized list certainly has an implicit order, but there may be repetition or gaps in the letters.
therefore you would have to set the value attribute for every list item for this to work as required.
i'm not sure this really does what you want.