I ran into an issue with a svn project today so I decided to create a new repository. The thing I didn't realize is that SVN has been upgraded to version 1.6.2 in Snow Leopard. This caused a major conflict with Zend Studio 6.1. When I tried to browse the repository with a project import it couldn't read the SVN tree.
After a lot of searching I figured out how to update the SVN plug-in.
Goto Help => Software Updates => Find and Install.
Select Search for updates of the currently installed features and click Finish.
When the search finishes check "Subversive update site 2.0.x".
Click the "Search" button. There should be an option listed called "Subversive update site 2.0.x". If you check the box you will get an error on a JavaHL 1.4.5 Win32 Binaries (Optional). Click the arrow to the left of to expose more options. Click the arrow to the left of "Subversive SVN Connectors" and uncheck all the JavaHL Win32 Binaries. This should allow you to install the new update.
When the update has finished Zend will prompt you to allow a restart. Once it closes you will have to restart it. You'll need to select the new SVN plugin. Goto Zend Studio for Eclipse => Preferences. Goto Team => SVN. Click the SVN Connector tab and select "SVN Kit (SVN/1.6.2 SVNKit/1.3.0)" from the SVN Connector down down.
You should be able to import a project from a new version of SVN without a problem.
I may have left out a key piece of resolving the SVN issue. I was trying many things at the time, and this might be one of the parts that made it work.
There is a new version of the SVNKit plug-in for eclipse. I don't have the exact steps at this moment to install them in Zend Studio, but the site has the steps for Eclipse and they're pretty close. You can view them here.