If I have a question about the TwentyTen theme, or the WordPress.com Stats plugin, should I label them [themes] [twenty-ten] and [plugins] [stats], or [theme-twenty-ten] and [plugin-stats]? I like the latter more, since they reduce confusion by being more explicit (this is not just about all kind of stats, but about the plugin with the slug "stats"). You can still search for all plugin- or theme-related question by using a wildcard.
Update: It seems we are split on this. We already have a large number of plugin-specific posts, and it would be much clearer if they could be re-tagged. Currently I have not done this because it seems there is no real majority (Doug, Mike and tnorthcutt like separate tags, EAMann, kevtrout and I prefer combined tags). I would however modify my proposal so that the plugin names comes first, to improve the autocompletion. So
After we have done this we could promote plugin-specific feeds to the plugin authors, so they can place them on their blogs and support areas (or even replace their own support forum with WordPress Answers). Thisof course does not depend on combined or split tags, but we need a decision so we can start re-tagging.
(But is this the best way to "vote" on this? I propose everyone leaves a comment, it gets confusing if I leave a comment and vote another similar comment up, then we won't know how to count that. Original commenters should maybe vote again, otherwise we don't know whether they have changed opinion. Or just create a new question?)