For version 4.2 the developers are working on a bunch of new or enhanced features. The complete list is here, but this is my take on the additions:
Openfire Integration - This will bring the ability to sync your availability with many different IM systems. I'm not a huge IM user so to me this will probably have limited usefulness.
Dimdim Integration - Dimdim is an open source web conferencing solution. Due to the distributed nature of many sipXecs installations, the integration of Dimdim project with sipXecs will be a great benefit to many.
New Voicemail System - I think the current Voicemail System works pretty well in most cases. It does fall down a bit with the dial by name directory so hopefully this will be addressed.
Branch Office Survivable Solution - I'm on the fence about this one. I've been setting up most customers with individual PBX's at each site. This simplifies the installation quite a bit. Each time I have to upgrade a HA installation I dread it because something always breaks. It sounds great to have a single system that is managed centrally, but in my book simplicity breeds reliability.
Bridged Line Appearances - This will be great for those small offices that just need to know "What line is that call on?".
Auto Attendant Improvements - Again, the AA is pretty good now. It just lacks the ability to have a live operator during the day. I usually end up routing calls to a Phantom user and have it do some time of day routing for how I want the calls to actually ring.
Call Detail Record Improvements - These can only get better. What is in the system now is not overly usable to an administrator.
Improved User Portal - The current user portal is pretty drab. While that is fine for administering the system, the user needs a little more pizazz. Here are some ideas that are being tossed around. Maybe users will actually use the portal if it is a little slicker!
Enhanced Directory Services - How about making it sync with Outlook or my Google Contacts? That would be pretty sweet.
Multiple ACD Servers in a Cluster - I wish they would just rip out the present ACD and put in one that works. The current ACD is junk mostly because it doesn't like it when you transfer calls out of Queue. Who cares about multiple ACD servers that still are useless.
E911 Notification by SMS - This will be a cool add-on to the detection of 911 dialing. When a user dials 911 in addition to being able to send an e-mail (as the system does now), the system will be able to send an SMS message.