I’ve got by now 277MB data in the directory /downloader/pearlib/download ... and after several updates through magento connect, there are multiple versions of packages in this directory.
Now I’m curious if I could delete these files (if they get placed somewhere els after download and install, like the files in /tmp/pear/download), or at least if I may delete older versions if they aren’t used any more.
I’ve never looked too closely at the data, but I know that it basically downloads another Magento install, essentially doubling your inode usage. It contains all the data needed for the upgrade, and obviously once it’s been applied throughout your install, no longer needed.
It should be cleared out everytime you use Magento Connect. If you use the web-based interface, I believe checking the box to clear sessions will do this for you.