Today, I had the problem of converting a timestamp to a readable time format inside excel. Not quite as easy as I would have hoped for, but the solution is fairly painless.
In the excel column you wish to display the date, you need to place the following formula.
=(((COLUMN_ID_HERE/60)/60)/24)+DATE(1970,1,1)
You would then need to replace COLUMN_ID_HERE with the cell that holds the timestamp. e.g. A1
The above formula can be simplified, but I think the above explains a little more what is actually being done to the data 
You would then need to format the cell to be dd/mm/yyyy hh:mm and you are done
worked perfectly
this worked too (http://blog.teddyber.info/index.php?post/unix-timestamp-to-excel-date-time)
=unixtimestamp/86400+25569
Nice! worked like a charm
The above formula can be simplified, but I think the above explains a little more what is actually being done to the data