Boudewijn Rempt is raving about how bad the recent switch from Ctrl+Enter to just Enter was for the "send message" key shortcut.
he notes quite rightly that the keyboard shortcuts for the chat window are in the chat window, while the global kopete shortcuts are in the kopete shortcut window. this is fixable, though not completely trivial it seems as one would need a KXMLGUIClient for the chatwindow around in the main window from time to time (e.g the time when the user wants to define shortcuts). this is going to mean having to subclass KXMLGUIClient simply to get at the protected setXMLFile method. oh, and go back to using the hand-rolled slotConfKeys in kopete's main window that was slated for removal when 3.2 support was dropped. this probably explains why it hasn't been done yet. =)
in any case, Enter is what people are used to in IM clients, unless you use ICQ, so its whath the majority of users expect. more importantly "Enter" works with how most people use IM clients, namely to pound out a short message and quickly send it. as it is (or rather, was) i answer the "Can kopete use just Enter?" question far too often on IRC, mailing lists and even *sigh* in person.
Boudjewin also said that "There is only one rule about making usable applications, and that is to keep your applications as consistent as possible with their environment". i totally agree that consistency is king, but it's not the only rule in usability. not even close. and it's not really a rule, either. more a "best practices" sort of thing. there are times when breaking theoretical consistency (these are all communication apps, so they should all behave the same!) works out to be more usable. and kopete is a great object lesson for us here.
people have focused on the type of application Kopete is (communication) and ignored the real issue which is the way Kopete and IM applications in general are used. email and news reading are similar, yes, but email and IM are rather different animals. they may both be used to communicate, but so are cell phones and signal fires (though they have rather different user interfaces).
IM is much closer to IRC than it is to email, and which IRC client has Control+Enter as it's "send message"?