We're doing a massive redesign of the partitioner for 11.1 and I'm not sure whether we can add ext4 support.
At this point of time, I'm sorry to tell we can't :( Neither we will support ext4, nor, for example nfs4. ENOTIME ... However, we accept patches :)) Actually, we'd be quite happy if the community contributed.
What about adding some text to the new partitioner page briefly outlining how to do this? e.g.
"Ext4: Not currently available in this partitioner tool - please select ext3 and, after installation, run tune2fs option option to convert."
There is a wiki page covering partitioning redesign here: http://en.opensuse.org/UX/Partitioner but that one covers almost exclusively user-interface aspect of the whole business and very technical information do not really fit there. However, a new page describing some partitioner tips and tricks could be added and we could, for example, link it from partitioner help text frozZzenB. -- \\\\\ Katarina Machalkova \\\\\\\__o YaST developer __\\\\\\\'/_ & hedgehog painter