Ubuntu 8.10 (Intrepid Ibex) now ships with Subversion 1.5
You can't use a svn 1.4 client and a svn 1.5 client on the same working copy.
While the subversion integration in Eclipse is great I still prefer to do some things on the command line and some with kdesvn.
Then you need to upgrade your subclipse plugin to subclipse 1.4
If you can - then upgrade to Eclipse 3.4
But Eclipse 3.4 doesn't run the latest stable version of PDT - and last time I tried to use an Integration build it was unusable - I may try again sometime but right now I want a small upgrade.
I followed this instructions here http://subclipse.tigris.org/install.html [1]
But Eclipse reported a "Network problem"
So I downloaded the zip file
http://subclipse.tigris.org/files/documents/906/43792/site-1.4.5.zip [2]
Unpacked it in a folder on my local webserver, pointed Eclipse at this location and the installation worked!
Phew - I have a working Eclipse for PHP development on Ubuntu 8.10
Links:
[1] http://subclipse.tigris.org/install.html
[2] http://subclipse.tigris.org/files/documents/906/43792/site-1.4.5.zip