Here’s one from my email:

I’ve done nothing on my WordPress site in ages but am about to put up a story. I see (and had heard) 3.0 was available to download.

Do you think I dare do it, here with nobody to help me if it all screws up? My feeling is that it should be OK as there must be millions in the same boat, but don’t want to if I am wrong!

I think you can do it!  The longer you wait, the more people will have found bugs and fixed them, but if you have time to focus on it it’s very doable.  Before you upgrade, you should make a backup of your site – either the content (through Tools -> Export) or the database (through the WP-DB-Backup Plugin).

Here are detailed instructions:  http://codex.wordpress.org/Upgrading_WordPress

Just follow the instructions carefully, and don’t panic.

You may have issues w/ your theme, or some plugins that will also need to be upgraded. If so, your backup will help you get fixed up. If you are worried about a particular theme or plugin, simply do a Google search for your theme name and “WordPress 3.0 upgrade” to see if anyone has posted words of caution to the internet.