Tags - the new keyword spam?

[mrplough]

I know this isn't exactly the right forum (whereis?) to discuss this subject, but I was wondering if search engines are going to start seeing tagging and tag clouds as opportunities to spam keywords.

How I've set it up now is to have 200 showing just in case, and the rest logged backend so they all have a chance of breaking into the cloud as it were. If it's an ever growing tagcloud of thousands of words, I would think this would be frowned upon eventually by the engines.

The opposite argument is that it's a useful way for people to search your site, and sites would never get penalised for using this tool. Most CMS out there use tags or similar these days.

Anyone got any strong opinions either way?