The “new” display of “on-click” applications, showing the logos, is not quite a “self-explanatory” as the old version, even though it is a lot prettier. 
On the current “one-click” screen, if no note is displayed you can run the application under either PHP4 or PHP5. If a note is displayed, the application requires the indicated version of PHP.
Both versions of PHP are available for you to choose for a given domain via the Manage Domains screen (select “edit” beside the domain name, and check the appropriate radio button).
–rlparker