Unpivot / uncrosstab support?

Hi,

I was wondering if Postgresql (8.3 or later) had an equivalent function to the MS-SQL function "unpivot"? I've spotted the user contributed crosstab which is similar to the "pivot" function, but I can't find an equivalent "uncrosstab".

Essentially what I'm trying to do is take a table like this...

clientID clientName contact1 contact2 contact3 contact4
----------- -------------------- ----------- ----------- ----------- -----------
1 ABC Corp 1 34 2 NULL
2 DEF Foundation 6 2 8 9
3 GHI Inc. 5 9 NULL NULL
4 XYZ Industries 24 NULL 6 NULL

...and get a result like this...

clientID ContactNumber ContactID
----------- ----------------------- -----------
1 contact1 1
1 contact2 34
1 contact3 2
2 contact1 6
2 contact2 2
2 contact3 8
2 contact4 9
3 contact1 5
3 contact2 9
4 contact1 24
4 contact3 6

Which can be accomplished with unpivot.

For more info I've stolen the example from http://weblogs.sqlteam.com/jeffs/archive/2008/04/23/unpivot.aspx

Thanks
Josh Vote