tablular data should be in a properly implemented table (with TH as well as TD tags etc.), for easy access and interpretation from assistive technology such as screenreaders..
(think of a blind guy trying to make sense of cell 200, row 200 in a big table.. the value contained in the cell is not good enough.. the user needs context.. (from the table headers etc) to know what the data means.. automatic programs (bots, spiders etc) and assistive technology rely on developers specifying data correctly in their markup (another example is using lists, for semantic grouping, rather than just a bunch of consecutive links.. the latter does not imply a relationship between the group, whereas the former does..)