Index fragmentation is naturally happens as an action of insert, deletes and updates. It is important to manage this fragmentation, if not you can have performance issue with range type queries.
SELECT OBJECT_NAME(IPS.OBJECT_ID) AS TableName , CASE WHEN i.name IS NULL THEN 'HEAP TABLE, NO INDEXES' ELSE i.name END AS IndexName , index_type_desc AS IndexType , index_depth , avg_fragmentation_in_percent , page_count FROM sys.dm_db_index_physical_stats(DB_ID(),NULL,NULL,NULL,'LIMITED') IPS JOIN sys.indexes I ON IPS.OBJECT_ID = I.OBJECT_ID AND IPS.index_id = I.index_id ORDER BY avg_fragmentation_in_percent
i love your blog, i have it in my rss reader and always like new things coming up from it.