I found OSLPreparedStatement does not work on 10.5.2(intel)
for NULL value of internal sqlite3 statement.
I think the following patch will fix this problem.

--- ../OmniGroup.orig_sql/Frameworks/OmniSQLite/OSLDatabaseController.m	2008-03-15 20:50:00.000000000 +0900
+++ Frameworks/OmniSQLite/OSLDatabaseController.m	2008-03-17 00:19:48.000000000 +0900
@@ -181,7 +181,7 @@
 	sqlite3_prepare(
 			sqliteDatabase, /* Database handle */
 			[sql UTF8String], /* SQL statement, UTF-8 encoded */
-			0, /* Length of zSql in bytes. */
+			-1, /* Length of zSql in bytes. */
 			&statement, /* OUT: Statement handle */
 			&remainder /* OUT: Pointer to unused portion of zSql */               
 			);

[Ken Case]

Thanks! We've included this fix in the latest source release (OmniFrameworks-2008-03-20.dmg).