Does that plugin work with the latest version of WordPress? It’s hard to be sure until you install it. After all, a plugin may work perfectly fine across over several versions of WordPress, but the author might have been too busy (or indifferent) to update the “Compatible up to” field and commit a change to the repository.
Now that doesn’t matter so much.
A new feature (currently in beta) has been added to the plugin repository. There’s now a “Compatibility” box with a dropdown selection box. Pick your WP version, and it will show aggregated data from people pushing the “Works” and “Broken” buttons.
A neat idea, providing people don’t try to skew the results by voting “Broken” because they have some sort of vendetta against a developer… I might be worrying too much, but I think it’s a good idea other than that possibility.