Some of the markup-phobics have some very valid points against the implementation of new tags. So let's take a look at a different approach:
Make tables separate from the article. Don't embedd them into the text but just refer to them like you do with images. Similar to "upload a new image" we would add a "create a new table". First it would ask you for a name of the table and for the number of fields. (You can change them afterwards, it's just easier to create enough of them in the beginning)
Then it will show you a mask with an array of textareas to enter the values of the table. Each Field would have a few buttons attached to make it merge with the cell to the right, left, below and above. And a button to make a coloured background.
Between each row and column there is a small button to add a new row/column. And above each column and in front of each row there's a button to remove the column/row.
Each cell of the table will accept all kinds of wiki markup of course, so you can add images, links, etc to any cell.
A Preview button will show the rendered table.
Perhaps one wants to show the merge-buttons only upon request for keeping the display simple.
I'm not sure whether this will become a PITA to edit a large amount of tables, and perhaps one would add an alternative text-markup entry page to create a table "the old way" for us keyboard junkies and mouse haters.
Those two table entry modes would have to be equivalent and tables created by the one have to be editable using the other method, of course.
Regards,
JeLuF