ID      Col1       Col2       Col3
1       val1
1       val2
1       val3

Desired result:
ID      Col1       Col2       Col3
1       val1       val2       val3

-- Prepare sample data
DECLARE	@Sample TABLE
	(
		ID INT,
		col VARCHAR(9)
	)

INSERT	@Sample
SELECT	0, '1' UNION ALL
SELECT	0, '1' UNION ALL
SELECT	0, '2' UNION ALL
SELECT	1, '1' UNION ALL
SELECT	1, '2' UNION ALL
SELECT	1, '3' UNION ALL
SELECT	2, '5' UNION ALL
SELECT	2, '5' UNION ALL
SELECT	2, '5' UNION ALL
SELECT	3, '6' UNION ALL
SELECT	3, '6' UNION ALL
SELECT	5, '8' UNION ALL
SELECT	5, '9' UNION ALL
SELECT	4, '7'

-- Stage the source data
DECLARE	@Stage TABLE
	(
		ID INT,
		rowID INT IDENTITY(0, 1),
		col VARCHAR(9)
	)

INSERT		@Stage
		(
			ID,
			col
		)
SELECT		ID,
		col
FROM		@Sample
ORDER BY	ID,
		col

-- Display the data
SELECT		ID,
		MAX(CASE WHEN recID = 0 THEN col ELSE NULL END) AS col1,
		MAX(CASE WHEN recID = 1 THEN col ELSE NULL END) AS col2,
		MAX(CASE WHEN recID = 2 THEN col ELSE NULL END) AS col3
FROM		(
			SELECT		s.ID,
					s.rowID - t.rowID AS recID,
					s.col
			FROM		@Stage AS s
			INNER JOIN	(
						SELECT		ID,
								MIN(rowID) AS rowID
						FROM		@Stage
						GROUP BY	ID
					) AS t ON t.ID = s.ID
		) AS d
GROUP BY	ID
ORDER BY	ID