I've got the following in debians bts:

ackage: gossip
Version: 0.24-2
Severity: normal

Checking the sources, we find:
src/gossip-new-chatroom-dialog.c:256
        switch (account_type) {
        case GOSSIP_ACCOUNT_TYPE_JABBER_LEGACY:
        case GOSSIP_ACCOUNT_TYPE_JABBER: 
		[...];
		break;
        case GOSSIP_ACCOUNT_TYPE_MSN:
		[...];
		break;
        case GOSSIP_ACCOUNT_TYPE_IRC:
		[...];
		break;
	default:
		g_assert_not_reached();
	}

where obviously the default branch is taken for account type
GOSSIP_ACCOUNT_TYPE_SALUT.

Making default the same as _MSN and _IRC (which is the same anyway
currently) makes it not abort, but obviously there needs to be some
telepathy query and those connections that aren't capable of doing chat
rooms ought to be ignored. In fact, with my setup, the Join New... menu item
shouldn't even be displayed because salut is the only connected transport
right now.

Stack trace:

+ Trace 135967

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: powerpc (ppc)

Kernel: Linux 2.6.22-rc1-g79e90214-dirty (PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages gossip depends on:
ii  gossip-common             0.24-2         friendly Jabber client for GNOME -
ii  libaspell15               0.60.5-1       GNU Aspell spell-checker runtime l
ii  libc6                     2.6~20070518-1 GNU C Library: Shared libraries
ii  libdbus-1-3               1.0.2-5        simple interprocess messaging syst
ii  libdbus-glib-1-2          0.73-2         simple interprocess messaging syst
ii  libgconf2-4               2.18.0.1-3     GNOME configuration database syste
ii  libglade2-0               1:2.6.0-4      library to load .glade files at ru
ii  libglib2.0-0              2.12.12-1      The GLib library of C routines
ii  libgnome2-0               2.18.0-4       The GNOME 2 library - runtime file
ii  libgnomeui-0              2.18.1-2       The GNOME 2 libraries (User Interf
ii  libgnomevfs2-0            1:2.18.1-1     GNOME Virtual File System (runtime
ii  libgtk2.0-0               2.10.12-2      The GTK+ graphical user interface 
ii  libloudmouth1-0           1.2.1-1        Lightweight C Jabber library
ii  libnotify1 [libnotify1-gt 0.4.4-3        sends desktop notifications to a n
ii  libpanel-applet2-0        2.18.1-2       library for GNOME 2 panel applets
ii  libpango1.0-0             1.16.4-1       Layout and rendering of internatio
ii  libtelepathy2             0.0.54-1       Telepathy framework - GLib library
ii  libx11-6                  2:1.1.1-1      X11 client-side library
ii  libxml2                   2.6.28.dfsg-1  GNOME XML library
ii  libxss1                   1:1.1.2-1      X11 Screen Saver extension library

Versions of packages gossip recommends:
ii  iso-codes                     1.0a-1     ISO language, territory, currency 

-- no debconf information