I didn't mention it on IrishGenealogyNews at the time because no additional information was provided and I don't like to point researchers in the direction of updates unless I have some clear idea on what 'updated' means. It might be additional records; it might be new or additional images joining a database; it might be a reconfiguration of search fields... Well, it's taken a while to find any information about this particular update but today I came across a tweet from @AncestryUK and it seems the update saw the addition of new records – no fewer than 80,874 of them, too.
The tweet advises that among the new items are letters asking for aid for families in need, providing important testaments to how difficult life became in the mid-19th century.
Ancestry's description of the collection is pretty good, and the material can be searched by name of individual or placename, or browsed by individual items.