Not seeing CCK fieldsets when you form_alter your form?
Key words and phrases
fieldgroup module in CCK $form no longer has fieldsets best approach to putting the taxonomy selectors on an edit form into a collapsible group Using cck to place them into a fieldsetTags
Description
In #drupal channel on IRC, mikey_p reminds that the CCK fieldgroup module has a weight of 9, so your module implementing hook_form_alter has to have a heavier weight (higher number) if you want to see that.

I took this knowledge from IRC and put it on the web where Andy was able to find it and make a proper post about it. Now someone just needs to bring this around and document it in a proper place on Drupal.org...