Jan,

The RulesEngine.GetLastGeneratedUniqueValue() returns the latest value generated in your transaction. If you call the method directly after inserting a record, it will return the value you want to know.

For tables with a single column primary key based on a domain that generates unique values, you could search for the latest value used with a function executing the SQL below:
    

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

-- Description:	function to retrieve current value of a sequence object used as primary key value for a given table

CREATE FUNCTION get_current_sequence_number
(
	-- Add the parameters for the function here
	@tableName sysname
)
RETURNS int
AS
BEGIN
	-- Declare the return variable here
	declare
		@currval int;

	-- Add the T-SQL statements to compute the return value here
	SELECT	@currval = CAST( seq.current_value as int )
	FROM	sys.sequences as "seq"
	WHERE 
		seq.name = 'SEQ_' + @tableName;

	-- Return the result of the function
	RETURN @currval

END
GO

Regards,

Robert