The Pope is resigning. This is a big deal not just because it will trigger off another conclave - it's always gothic whenever a prominent office, whether potent or figurehead, is filled by election by a small body of voters; see previous remarks here about the Chancellorship of Oxford University, another normally lifetime job - but because he's the first pope to resign in nearly 600 years, since two competing popes resigned at once to clear the boards to end the Great Schism. He cites age and infirmity, two factors rendered more likely to hit by modern life-extending medical science. It's critical in the case of the Pope, who is usually elected old and serves older, because he is not normally a figurehead but the actual leader of his Church.
Queen Beatrix of the Netherlands is also resigning, or abdicating as it's called for royalty. She is also a senior citizen, but considerably younger than the Pope. (She's 75, he's 85.) No election is needed here; she has an heir in place, and her job is mostly ceremonial and nominal; there's no reason to drag it out. Her mother and grandmother before her did the same.
Queen Elizabeth of Her Various Realms and Territories is not resigning. She's in good health, we hear, though she's older, by a year, than the Pope. (Rule of thumb: You know you're getting old when you're older than the President of the U.S. You know you're actually old when you're older than the Pope. And you're truly mindbogglingly venerable when you're older than the President of the LDS Church, but that's another story.) And her job is even more ceremonial than Beatrix's: both queens certify governments, which in the U.K. is almost always a nominal process; in the Netherlands, due to a more complex party system, it's a bit more complicated than that. And a monarch of the U.K. stands on a lot more ceremony than one from the more easy-going Low, or Scandinavian, countries.
The question of whether a voluntary resignation by a Pope or a monarch could lead to pressure on future incumbents to resign involuntarily has been raised. It's also been raised in regard to assisted suicide. It was even raised by Richard Nixon in an attempt to forestall his resignation, first ever by a U.S. President, but the precedent doesn't seem to have had much effect on his successors so far. Abdication due to a desire just to hang it up is considered beneath the dignity of a U.K. monarch, due to all that ceremony, I guess. (Abdication for more pressing reasons, most recently practiced in 1936, is another matter.) Still, there's her successor waiting in the wings, only ten years younger than Beatrix, and now older than his venerable great-great-grandfather Edward VII was when he finally succeeded his even more venerable mother Victoria.