Just a quick point of clarification. WordPress 2.2 is a mandatory security upgrade for WordPress 2.1.3 users. There will be no further releases in the 2.1.x branch. 2.2 includes security fixes that 2.1.3 lacks, so your only upgrade path is to 2.2.
The good news is that although a lot of under-the-surface code changed in 2.2, it’s not jarringly different from a usage standpoint. So if familiarity was holding you back from upgrading, it shouldn’t be.
Mark on WordPress 
Thank you for making this known. 🙂
Along with the bug fixes, WordPress 2.2 brings new bugs to the table: wp_mail removes the Content-Type, you can’t remove widgets in Firefox and all widgets are used by default… etc. You can check the bug list at trac.wordpress.org
The official install guide is quite hard to understand so i decided to write a tutorial with pictures about how to upgrade to wordpress 2.2 and i allso describe the compatibility issues on widgets.
I’ve been using WP 2.2 for the last few days and honestly, from an author’s standpoint, I can hardly see any difference!
I know there’s been a lot of work “under the hood” but upgrading from 2.1.3 has been painless… for me, at least.
Goeie dag!
Check this out!
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And some more..
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Mark, will you provide patches for 2.2.2 -> 2.2.3?