Today PostGIS 1.5.0 reached Stack builder. That means that if you are using windows it’s now very simple to try the new functionality. Thanks Regina and Leo
That means that a fully functional installation with PostGreSQL 8.4.2 and PostGIS 1.5.0 is just a few clicks away.
Download the oneclick-installer of PostGreSQL from
http://www.enterprisedb.com/products/pgdownload.do#windows
Then, in the end of the installation choose yes to start Stack builder and mark PostGIS 1.5 under spatial extensions.
Ready to go 