Oh, that’s weird, because I just wrote this in the last two days and posted the article this morning: http://www.powershelladmin.com/wiki/An_Advanced_Cmdlet_to_Merge_Csv_Files_in_PowerShell
I swear I’m psychic sometimes.
I hadn’t seen this before doing that. It works with custom PowerShell objects (like the ones created from Import-Csv), so I might as well have named it Merge-Object, or, indeed, Join-Object, I guess. I didn’t read the article on MSDN thoroughly yet, but it looks like similar functionality. I bet mine sucks in comparison? 