This is brack. (Or "barm brack", depending on who you're talking to, "barm" being an old word for yeast.* [The page with the recipe at Edible Ireland below suggests a different Irish etymology, which for all I know is also correct. But "barm" certainly came to mean yeast in the 18th-19th centuries in English-language usage.])
People sometimes ask me what happens in Ireland at Halloween (possibly with reason, as indications are that it was invented here.)
One of the things that happens is that this starts turning up in the stores. It's a fruit bread, basically, with raisins and sultanas: quite a nice one if done well.
It comes to you with a ring baked in (and sometimes with a coin as well, and/or other similar small tokens). It used to be a sort of fortunetelling game: when the brack was cut up and served out, if you got the coin you'd get rich, if you got the ring you'd get married, and so forth. (See the Wikipedia page for a bit more detail on this.) That this sort of game associated itself with the holiday in Ireland is no particular surprise. Folkloric tradition right across Europe in previous centuries held that during the period around All Saints' Day and All Souls' Day the walls between the worlds or the various states of being were thinner than usual, the dead then being able to make arcane or hidden knowledge (such as one's future fate) known to the living. So fortunetelling games associated with the season popped up all over the place in European folk culture.
Cf. the page on Irish Halloween traditions here. There are also a couple of pretty fair looking recipes here and here. (And of course our own recipe at EuropeanCuisines.com, in which the raisins are plumped up with whiskey and then the whole cake is inoculated with it after the fact. Our recipe doesn't use yeast as the rising agent, but believe me, you won't care. It's really good.)
ETA: So there you see it cut as well. This one has candied fruit in it as well. Nice, a light texture, not too sweet, toasted very nicely. The ring is still in the main chunk somewhere.
*And of course the word "barmy" implies that somebody's brains, manner or intellectual output have gone as frothy as bubbling-up yeast, but we don't need to go there right now.
