It appears that the problems with BlogRolling's recently-updated feature have been corrected, as about half of my blogroll is now showing a reasonable last-updated time.

UPDATE: Here's what BlogRolling has to say:

We had a temporary issue with the blogrolling database. It seems the table had been abused and resulted in it beeing a little battered. We have made repairs to the table and things are back up to speed.

Also please be advised that we are experiencing difficulties in regards to some blogs not receiving proper updates and notification of these blogs are not been displayed within your blogrolls. We are currently implementing a better way to keep a hold on updated blogs.

Cheers!

My earlier entries on BlogRolling's problems (and a workaround) are here and here.