One of my biggest complaints about Lightroom's catalog backup feature is that they offer you no functionality to prune your old backups after a certain date or number of existing backup sets. Lightroom will happily keep backing up your catalog until your hard drive is full.
I've long maintained that it shouldn't be that hard for Adobe to add some sort of feature that would only keep "x" number of backups or would delete backups of a certain age. I'm not sure why they haven't added the feature in LR3 or LR4.
Fortunately, a third party solution has emerged to fill in this gap.
Here's the official description from their website:
This plugin doesn't interfere with the standard Lightroom backup process at all. Instead, it runs when Lightroom starts and identifies backups which are too old, and then deletes them. You specify how old is too old, and you can also say the smallest number of backups you want to keep.
Once it's set up, you just forget about it - just like the backups.
This is, of course, exactly what I've been asking for from Adobe. And for £5.00 ($7.75 U.S.), this seems like a pretty good deal.