The PEAR blog has posted some handy instructions for those out there that want to get PEAR and PEAR2 checkouts working from the new Subversion repository (recently moved from CVS).

Now that pear2 is in svn.php.net, it is possible to do commits with multiple packages using a feature of subversion called "sparse checkouts." [...] Here is the version I used to set up pear and pear2 in a way that will allow committing to both pear and pear2 packages in a single commit.

Rasmus Lerdorf has written about the same thing for the main PHP side of things. All the commands you'll need are there to get things set up and working more efficiently.