My solution for http://beyondrelational.com/puzzles/challenges/96/home.aspx

gistfile1.sql

WITH 
  [Nums1] AS (SELECT 1 AS [Value] UNION SELECT 2 AS [Value])
, [Nums2] AS (SELECT A.* FROM [Nums1] AS A, [Nums1] AS B, [Nums1] AS C)
, [Nums3] AS (SELECT A.* FROM [Nums2] AS A, [Nums2] AS B, [Nums2] AS C)
, [Nums4] AS (SELECT A.* FROM [Nums3] AS A, [Nums3] AS B)
, [Nums] AS (SELECT TOP(1000) ROW_NUMBER() OVER(ORDER BY (SELECT 0)) AS [n] FROM[Nums4])
, [Data] AS (SELECT 1 AS [id], N'The upcoming release of SQL Server is codenamed Denali. It is also called SQL11 which refers to version 11 and peple misunderstand it to be SQL Server 2011.' AS [comment] UNION SELECT 2 AS [id], N'SQL Server Denali CTP 3 introduced a number of TSQL enhancements.' AS [comment])
, [Sentences] AS (
	SELECT [id]
		 , [comment]
		 , LTRIM(SUBSTRING([comment], MIN([n]), MAX([n]) - MIN([n]))) AS [data]
		 , ROW_NUMBER() OVER(PARTITION BY [id], [comment] ORDER BY MIN([n])) AS [sentence]
	FROM [Data] 
	CROSS JOIN [Nums] 
	WHERE [n] <= LEN([comment])
	GROUP BY [id], [comment], CHARINDEX('.', [comment], [n])
)
, [Words] AS (
	SELECT [id]
		 , [comment]
		 , [sentence]
		 , [data]
		 , MIN([n]) AS [begin]
		 , MAX([n]) AS [end]
		 , SUBSTRING([data]
		 , MIN([n]), MAX([n]) - MIN([n])) AS [part]
		 , ROW_NUMBER() OVER(PARTITION BY [id], [comment], [sentence], [data] ORDER BY MIN([n])) AS [WordNumber]
	FROM [Sentences]
	CROSS JOIN [Nums]
	WHERE [n] <= LEN([data]) + 1
	GROUP BY [id], [comment], [sentence], [data], CHARINDEX(' ', [data], [n])
)
, [WordGroups] AS (
	SELECT [id]
		 , [comment]
		 , [sentence]
		 , [data]
		 , MIN([begin]) AS [begin]
		 , MAX([end]) AS [end]
		 , SUBSTRING([data], MIN([begin]), MAX([end]) - MIN([begin])) AS [text]
	FROM [Words]
	GROUP BY [id], [comment], [sentence], [data], ([WordNumber] - 1) / 5
)
, [NumberedWordGroups] AS (
	SELECT [id]
		 , [sentence]
		 , RANK() OVER(PARTITION BY [id], [sentence], [data] ORDER BY [begin]) AS [group]
		 , [text]
	FROM [WordGroups]
)
	SELECT *
	FROM [NumberedWordGroups]
	ORDER BY [id], [sentence];