This time if you upgrade you don't lose your previous version
Nokia has smartly renamed dll and pyd files with a suffix 251_ so both version can co-exist on the same device Only problem is Python shell has same name and same icon but you can put your new icon in a new folder named ie python190
You can note that sourceforge is not used this time for the new version but maemo garage site !
PyS60 2.0 will have new modules like touch ui support (5th edition). Until 2.0 (stable version) there will many 1.9.X (unstable) !
PyS60 hits 1.9, though you might not want to upgrade yet
Python for S60 has been almost totally rewritten, it seems (around the Python 2.5.1 core), with a huge version number jump to v1.90, available here. The most obvious changes are for developers, including a new GUI-driven SIS packaging tool and far better support for 'standard' Python libraries. Here's the download page, here's the readme that you'll want to scan over and here's where I read about it.