I mean, we've all heard of jailbroken Iphones being vulnerable to worms exploiting the fact that all jailbroken phones had the same root password, now, I've already changed mine, but is there any danger?
Do we need to be aware? what else do we need to do?
Practically everyone here roots their phone...

As long as you ONLY install applications from Nokia repositories (i.e. maemo.org), then you will be fine.

Generally speaking though the N900 does not need to be 'rooted' as it's open source anyway, and you can access root easily. And it's pretty secure aswell.

Rooting as you put it, is normal on Linux, nothing to worry about.

Cool thanks.

Sorry, I don't think it's quite that simple. There are several servers available in the extras repositories. Any of these servers could contain exploits that would allow others to connect to your phone. It becomes a question of how up to date these applications are and how secure their upstream project is.

Also, even perfect server applications with no exploits rely on your root password being reasonably picked to not be susceptible to a dictionary attack.

Hope this helps.

Frank

And the number of users apparently affected by this "problem" is?

My guess is zero. This is a theoretical problem that you can worry about if you really like to worry.

It is a valid concern, there are linux worms I've read?

Frank Banul, you do make a valid point and it is possible, but I don't think we should confuse the matter.

If the OP doesn't understand the Linux 'root' command and what it does, then it's best to just keep it simple.