Database Indexing - Maintenance Jobs
Reorganizing an index does not update the statistics on an index.  Reorganize will ensure that the B+ tree is balanced, since SQL Server doesn't auto balance trees during operation.  Rebuilding an index will recreate the index, allowing the engine to update the statistics on an index.

You should consider periodically reorganizing and updating statistics on lightly fragmented queries granted you can spare the maintenance time.  You can also try to update statistics periodically using samples, if your data is homogenous enough.

You can read more about Update Statistics here

http://msdn.microsoft.com/en-us/library/ms187348.aspx

Kimberly Tripp blogs heavily on index maintenance on http://sqlskills.com

Check out her links for Statistics and Indexes.