I have been using this since then without any trouble. But today I tried using it to centre-align column headings in the top row by using <1colc>. While it works for other columns, it does not work on the last column.
;;; Multi-column Table Cells
;;
;; Export table cells with multiple columns using Latex-like syntax.
;; For example in the following the "<3colc>Backends" cell spans 3
;; columns with it's text centered.
;;
;; | | <3colc>Backends | | |
;; | | LaTeX | HTML | Text |
;; |-----------+-----------------+-------+-------|
;; | extension | .tex | .html | .txt |
;;
;; The `org-export-multicolumn-filter-latex' function is taken from
;; the following.
(defun org-export-multicolumn-filter (row backend info)
(cond
((org-export-derived-backend-p backend 'latex)
(org-export-multicolumn-filter-latex row backend info))
((org-export-derived-backend-p backend 'html)
(org-export-multicolumn-filter-html row backend info))))
(defun org-export-multicolumn-filter-latex (row backend info)
(while (string-match
"\\(<\\([0-9]+\\)col\\([lrc]\\)?>[[:blank:]]*\\([^&]+\\)\\)" row)
(let ((columns (string-to-number (match-string 2 row)))
(start (match-end 0))
(contents (replace-regexp-in-string
"\\\\" "\\\\\\\\"
(replace-regexp-in-string "[[:blank:]]*$" ""
(match-string 4 row))))
(algn (or (match-string 3 row) "l")))
(setq row (replace-match
(format "\\\\multicolumn{%d}{%s}{%s}" columns algn contents)
nil nil row 1))
(while (and (> columns 1) (string-match "&" row start))
(setq row (replace-match "" nil nil row))
(decf columns))))
row)
(defun org-export-multicolumn-filter-html (row backend info)
(while (string-match "class=\".*\" *><\\([0-9]+\\)col\\([lrc]\\)?>" row)
(let ((columns (string-to-number (match-string 1 row)))
(start (match-end 0))
(algn (case (intern (or (match-string 2 row) "l"))
(c "center")
(r "right")
(l "left"))))
(setq row (replace-match
(format " class=\"%s\" colspan=\"%s\">" algn columns)
nil nil row))
(while (and (> columns 1)
(string-match "<th .*> </th>" row start))
(setq row (replace-match "" nil nil row))
(decf columns))))
row)
(add-to-list 'org-export-filter-table-row-functions
'org-export-multicolumn-filter)