JCE Editor 1.5.0 beta 4 has been released along with an update to the Admin Component, File Manager and Media Manager plugins. The Image Manager Extended also joins the bunch with its first beta in 1.5.0!
This is sort of a milestone release as it includes the new JCE Groups Permissions System, which adds a powerful and versatile method to control acces to the JCE Editor's features. There is a full tutorial on JCE Groups , I suggest you go through it after installing the new versions. Like sharks with lasers, the new JCE Groups system is awesome, but the concept can be a little confusing at first, especially to users used to the old system.
Another new and exciting feature is the Advanced Code Editor plugin, included in the core, which adds syntax highlighted code editing to the HTML view (the popup, not the toggle view). Its got a similar icon to the HTML view, but is red instead 
One other change to take note of is that the AdvLink icon has changed. This is to differentiate it from the Link icon. The new icon is 
None of the versions released to day are compatible with anything released before. The required versions are:
Please report bugs where you find them and post suggestions etc in the forum. Please remeber that this is still beta code, so use with caution (ie: test it before using it live!)