update has no effect

Hi,
I successfully applied this update earlier today, to a test site, and both the 'modules' page 'available updates' page are correctly reporting rc8. If I were you I'd double check that your new CCK files are where they should be.

(As a test, I temporarily edited the version string in CCK's content.info file and it changed the version number shown on the 'available updates' page for CCK, and for 'content' in the CCK section of the 'modules' page. CCK's other modules reported versions remained unchanged because they have there own .info files.)

I have exactly the same behavior, only I am downloading via the browser to Mac OS and unpacking locally.

I drag the cck folder into sites/all/modules and go and check the 'modules' and 'updates' file and they report rc7 and advise me of an update.

I've been through the hoop several times now and feel like a monkey.

Can it have anything to do with the presence of other CCK modules in my system?

I have cck_blocks and cck_fieldgroup_tabs in my system

Any time you have weird problems like this I would try disabling all modules other than the ones in question to see if it changes anything. It is possible that other CCK modules could be interfering so I would disable them to see what that does. You may want to both disable them and temporarily remove them from the modules folder just to be sure they're not having any impact on your results.

If you're using the tarball, be sure to empty the cck folder out before downloading a new copy in case you have old files floating around in the wrong places.

Well I'm glad you found the problem :)