OK, I got more than 30 sites in WP running on 2.9.something version and there is a question should I update to 3.0? I'm well aware of what my brain is telling me to do - updating is always smart and useful and sometimes a must to prevent possible security issues. But I have 30+ sites and it would take a long time. My question is: how much is WP 3 going to mess up my themes and well tweaked settings from 2nd version?

Depending on the theme the answer could be no effect at all or it could be a nightmare.

For security reasons it's always worth the hassle of upgrades though.

I really don't see that it takes that long - a few seconds per site. Like Blue said, leaving them as is opens your sites to malware/hacks.

As Blue and Steve said, for security reasons, you should definitely upgrade. Upgrading WordPress is extremely simple, so it's there is really no reason not to.

However, if you don't mind your WordPress being hacked and all your posts deleted, etc., then don't worry about it.

Are you aware of the gaping hole in the 2.9 version? We've seen many MANY sites with code injections due to the outdated version.

Themes are always an issue as sometimes they may not work, but test it out - I've had very few themes that couldn't withstand the upgrade, and those that couldn't usually had an upgraded theme available anyway.

Going from 2.9 to 3.0 was a big change in code, and a lot of holes patched and fixed. It's definitely worth the time invested to get your site back on track and secure.

Thanks guys about that. I guess it's inevitable to upgrade. I was just thinking out loud. It's always boring to do those small things that have no direct impact on money making.

Make sure the theme and plugin you are using are compatible with the higher version. If not sure, test the same on local system before updating on real server.

I have updated more than 20 WP installations and never had a problem.

I too was afraid that something might go wrong at first, being a major upgrade, but so far so good. I recall just one widget being incompatible, but it wasn't even activated anyway.

3.0.4 is also a very important update in terms of security.

As long as your themes are not too old, they should work as is, but may not support the new things like custom menus, that comes with version 3.

This is where an auto-installer would help you out. Had you used installatron or softaculous to install these, making backups, upgrading and restore those that didn't upgrade would be a trivial matter. (Somthing to look for in a host in future).

If you have lots of modules installed I would suggest doing a manual upgrade as appose to using the auto-installer. We find it works best.

You should first backup the current WordPress 2.9 installed before move on to WordPress 3.0.
You can smoothly update to Wordpress 3.0.4.