How to get lowest, common parent for 2 rows in recursive table (SQL)

Let's say that we have we have a table with the classic 'manager id' recursive relationship:

Users user_id int manager_id int (refers to user_id)

If you randomly select 2 rows in the table- or 2 nodes- how do you find the lowest level, common ancestor? My platform is SQL Server 2005 (Transact-SQL) but any ANSI compliant SQL will also work...

From stackoverflow

• WITH
      hier1 (id, parent) AS (
      SELECT id, parent
      FROM table l
      WHERE id = @user1
      UNION ALL
      SELECT id, parent
      FROM table l, hier1 h
      WHERE l.id = parent
      ),
      hier2 (id, parent) AS (
      SELECT id, parent
      FROM table l
      WHERE id = @user2
      UNION ALL
      SELECT id, parent
      FROM table l, hier1 h
      WHERE l.id = parent
      ),
  SELECT  TOP 1 hier1.id
  FROM    hier1, hier2
  WHERE   hier1.id = hier2.id
  

• A few minor edits to Quassnoi's answer, and it works:

  WITH
      hier1 (id, parent) AS (
      SELECT      id, parent
      FROM        table
      WHERE       id = @user1
      UNION ALL
      SELECT      id, parent
      FROM        table l, hier1 h
      WHERE       l.id = h.parent
      ),
      hier2 (id, parent) AS (
      SELECT      id, parent
      FROM        table
      WHERE       id = @user2
      UNION ALL
      SELECT      id, parent
      FROM        table l, hier1 h
      WHERE       l.id = h.parent
      )
  SELECT  TOP 1 hier1.id
  FROM    hier1, hier2
  WHERE   hier1.id = hier2.id
  

  Quassnoi : What were the edits? I don't see any difference :)