Cleaner dates in summary buffers

[João Távora]

Hi all,

Is there any way to turn this

    U.  2013-08-30 16:37  [    Julien Cubizolles    ]    `->              
    U.  2013-08-30 10:16  [         F. Gr.          ]  custom-theme-load-p
    U.+ 2013-08-30 15:07  [   jumianek@gmail.com    ]  v mouse does not co
    U.+ 2013-08-30 17:35  [      Óscar Fuentes      ]  `-> 
    U.  2013-08-30 23:27  [        Catonano         ]  v o-blog (helpwith 
    U.  2013-08-31 02:12  [      Jambunathan K      ]  `-> 
    U.  2013-08-31 22:26  [        Catonano         ]    `->

Into this?

    U.  2013-08-30 16:37  [    Julien Cubizolles    ]    `-> 
    U.             10:16  [         F. Gr.          ]  custom-theme-load-p
    U.+            15:07  [   jumianek@gmail.com    ]  v mouse does not co
    U.+            17:35  [      Óscar Fuentes      ]  `-> 
    U.             23:27  [        Catonano         ]  v o-blog (helpwith 
    U.  2013-08-31 02:12  [      Jambunathan K      ]  `-> 
    U.             22:26  [        Catonano         ]    `->

I already have these settings

    (setq gnus-summary-line-format "%U%R%z %(%&user-date;  %[%ux%]  %B%s%)\n"
          gnus-user-date-format-alist '((t . "%Y-%m-%d %H:%M"))
          gnus-thread-sort-functions '(gnus-thread-sort-by-date))

    (defun gnus-user-format-function-x (header)
        ;;; stuff that fancies up the sender name)

And some more settings, probably irrelevant. I'm thinking I could write
code in `gnus-summary-update-hook' that hides these dates with a
'display property, but wonder if you can come up with anything better...

Thanks,
João