Smark - 9:35 pm on Feb 7, 2008 (gmt 0)

If you would like to make the the changes revesible I can suggest to hide some content and links on every page from Google with googleon/off tags.
The example: <!--googleon: all--> Text <!--googleoff: all-->
You can later remove these tags. All content will be added again.

These tags are Google specific. Other search engines will still index the whole content because they don't understand these tags. I don't know exactly if they have similiar SE specific tags.

You can use also use rel="nofollow" to hide some internal links and pages from search engines.