DECLARE @Dates TABLE (ID INT IDENTITY, Date DATETIME)
-- Credit to Itzik Ben-Gan for the spiffy query to create a table of numbers then converted to dates
;WITH Nbrs_3( n ) AS ( SELECT 1 UNION SELECT 0 ),
          Nbrs_2( n ) AS ( SELECT 1 FROM Nbrs_3 n1 CROSS JOIN Nbrs_3 n2 ),
          Nbrs_1( n ) AS ( SELECT 1 FROM Nbrs_2 n1 CROSS JOIN Nbrs_2 n2 ),
          Nbrs_0( n ) AS ( SELECT 1 FROM Nbrs_1 n1 CROSS JOIN Nbrs_1 n2 ),
          Nbrs  ( n ) AS ( SELECT 1 FROM Nbrs_0 n1 CROSS JOIN Nbrs_0 n2 )
INSERT INTO @Dates(Date)
SELECT DATEADD(dd, num, CAST('01/01/2012' AS DATETIME) -1) AS Date
FROM (SELECT ROW_NUMBER() OVER (ORDER BY n) AS num
	FROM Nbrs ) t
WHERE DATEADD(dd, num, CAST('01/01/2012' AS DATETIME) -1) BETWEEN '01/01/2012' AND '12/31/2012' 

SELECT *,CASE WHEN t.StartDate > [Date] THEN ROUND((DATEDIFF(ss, StartDate, DATEADD(dd, 1, d.[Date])) / 60.00),2) 
			WHEN d.[Date] = CAST(t.EndDate AS DATE) THEN ROUND((DATEDIFF(ss, d.[Date], t.EndDate) / 60.00),2)
			WHEN d.[Date] < t.EndDate THEN ROUND((DATEDIFF(ss, d.[Date], DATEADD(dd, 1, d.[Date])) / 60.00),2)
		END
FROM (SELECT 1 AS PatientID, '2012-10-15 10:00:00' AS StartDate, '2012-10-17 08:59:00' AS EndDate UNION
	SELECT 2 AS PatientID, '2012-10-11 08:00:00' AS StartDate, '2012-10-16 12:59:00' AS EndDate) t
INNER JOIN @Dates d ON d.Date BETWEEN CAST(t.StartDate AS DATE) AND t.EndDate
ORDER BY PatientID, StartDate

DECLARE @T TABLE (PatientID INT, StartDate DATETIME, EndDate DATETIME)

INSERT INTO @T
SELECT 1, '2012-10-15 10:00:00', '2012-10-17 08:59:00'
UNION ALL SELECT 2, '2012-10-11 08:00:00', '2012-10-16 12:59:00'

;WITH Tally(n) AS (
    SELECT TOP (SELECT 1+MAX(DATEDIFF(dd, StartDate, EndDate)) FROM @T)
        ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1
    FROM sys.all_columns a CROSS JOIN sys.all_columns b)
SELECT PatientID, StartDate, EndDate, CAST(Date AS DATE)
    ,Minutes=CASE WHEN DATEADD(dd, 0, DATEDIFF(dd, 0, StartDate)) = Date
                    THEN DATEDIFF(minute, StartDate, Date+1)
                  WHEN DATEADD(dd, 0, DATEDIFF(dd, 0, EndDate)) = Date
                    THEN DATEDIFF(minute, Date, EndDate)
                  ELSE 1440 END
FROM @T
CROSS APPLY (
    SELECT DATEADD(dd, n, DATEADD(dd, 0, DATEDIFF(dd, 0, StartDate))) 
    FROM Tally
    WHERE n BETWEEN 0 AND DATEDIFF(dd, StartDate, EndDate)) b (Date)
ORDER BY PatientID, Date

DECLARE @T TABLE (
  PatientID INT,
  StartDate DATETIME,
  EndDate   DATETIME)

INSERT INTO @T
SELECT 1,
       '2012-10-15 10:00:00',
       '2012-10-17 08:59:00'
UNION ALL
SELECT 2,
       '2012-10-11 08:00:00',
       '2012-10-16 12:59:00';

WITH Tally(n)
     AS (SELECT TOP (SELECT 1+Max(Datediff(dd, StartDate, EndDate)) FROM @T) Row_number() OVER (ORDER BY (SELECT NULL)) - 1
         FROM   sys.all_columns a
                CROSS JOIN sys.all_columns b)
SELECT PatientID,
       StartDate,
       EndDate,
       Cast(Date AS DATE),
       Minutes=CASE
                 WHEN Dateadd(dd, 0, Datediff(dd, 0, StartDate)) = Date THEN Datediff(minute, StartDate, Date + 1)
                 WHEN Dateadd(dd, 0, Datediff(dd, 0, EndDate)) = Date THEN Datediff(minute, Date, EndDate)
                 ELSE 1440
               END
FROM   @T
       CROSS APPLY (SELECT Dateadd(dd, n, Dateadd(dd, 0, Datediff(dd, 0, StartDate)))
                    FROM   Tally
                    WHERE  n BETWEEN 0 AND Datediff(dd, StartDate, EndDate)) b (Date)
ORDER  BY PatientID,
          Date