Holy Communion on the tongue whilst kneeling: mandatory

At least that's now the case in the Cathedral of Lima, Peru.

From Rorate Caeli:

To receive holy communion at the Cathedral-Basilica of Lima, Perú, the faithful must now kneel in addition to receiving only on the tongue. For that purpose, two kneelers are now put before the steps of the high altar at the moment of Communion, just like in Papal Masses.

In his sermon on September 20, 2009 in the Cathedral, Juan Luis Cardinal Cipriani Thorne, Archbishop of Lima, made the following statement:

"The most respectful way of receiving the Eucharist is kneeling and on the tongue. We must recover a sense of respect and reverence due to the Eucharist, because the love to Jesus is the center of our Christian lives. Our souls are at stake."

The Archbishop -- who has tried to make Lima a "Eucharistic City" -- also exhorted his flock to adore the Eucharistic Lord in the more than 70 adoration chapels in the city.

Of course, we should remember it's also the universal law throughout the Church already.  It's only indults (exceptions) that permit local bishops to allow faithful to receive any other way. 

The spurious argument that "but just because we receive in the hand and standing doesn't mean we express any lesser respect and reverence to the Eucharist" sort of misses the point: 40 or so years of this practice has played a part in lessening belief in the Real Presence, but not making it abundantly clear to all at all times, what we believe is happening and what the Eucharist really is.