The new feature adds an action to the "Edit" menu that activates word wrap in all open text-editors of your workbench. This is of course not persistent and will turn back to normal (deactivated word wrap) on the next start of Eclipse. This may change if the word wrap plug-in and line number ruler fix will make it as a bug-fix into the main Eclipse release.
Please note that the execution can take a few seconds because if there are many inactivate editors they will be activated one after the other. In fact, if you left five editors open when you closed Eclipse there will be one active and four inactive editors on a restart. When you click on one of the tabs (and therefore switch to another editor) it will be activated. This is what the new feature has to do for every inactive editor (but without giving you any visual feedback apart from the activated word-wrap on your current text editor).
If you are new to the Eclipse word-wrap plug-in please have a look at the project website and install it by using the update site.
I really appreciate any feedback or bug reports! Please comment on this post or send me an email if you encounter any problems.