I've created following test case in JPAQLComplianceTest.java:
public void testOrderByAlias() {
Session s = openSession();
s.createQuery( "select c.name as myname FROM Item c ORDER BY myname" ).list();
s.close();
}
and it fails:

Caused by: java.sql.SQLException: Column not found: MYNAME in statement [select item0_.NAME as col_0_0_ from EJB3_ITEM item0_ order by myname]
at org.hsqldb.jdbc.Util.throwError(Unknown Source)
at org.hsqldb.jdbc.jdbcPreparedStatement.<init>(Unknown Source)
at org.hsqldb.jdbc.jdbcConnection.prepareStatement(Unknown Source)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:534)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:452)
at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1598)
at org.hibernate.loader.Loader.doQuery(Loader.java:718)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:271)
at org.hibernate.loader.Loader.doList(Loader.java:2273)
... 30 more

Spec says in '4.9 ORDER BY Clause' that 'order by alias' is supported by JPA 2.