Some might be a tad outdated and have irrelevant information, but for the most part, the powers have stayed the same. Even the worst guides will give some insight into building a mastermind.
The first step in being sane is to admit that you are insane.
are there places to find more recent guides?
Nope, this is it. The masterminds' forum is where the guides are all at.
If you have a specific question, I'm sure folks would be happy to answer it.
From what I know (and others have said in this thread) the powers and the MM a/t itself have not changed much over the years. There have been QoL improvements, but that's about it.
The guides are just that - guides (some have builds in them, but iirc most are pre-IO enhancements). Mids is a brilliant tool to help you plan your character, and as GB has said, if the guides that are here don't answer your question, post it in the MM forums and I'm sure it'll get answered.
In the guide to guides section for masterminds, which guides (cookie cutters) are still ok to use as reference material?