I subscribe to Software Field Bulletins from Siemens (both NX and I-DEAS NX) and I haven't seen anything yet for NXI6m1.
Siemens usually doesn't make announcements for target release dates of bug fixes (maintenance releases), unless you ask a Siemens employee on the bbsnotes boards. They usually just send out a SFB informing subscribers that the new maintenance release is available for download.
There are I-DEAS only newsgroups available on bbsnotes, which is where I would ask this very question if I was really really wanting to know. You'll need to create a webkey account in order to access the newsgroups. If you need further help, post back in this thread and I can try to assist you.
There aren't any interface changes as far as i can tell. I think you already have the one change I have noticed, you can pan and zoom with the mouse in drafting. i think most of the changes have to do with fixing bugs and making it easier to transition to NX.
If you are looking to migrate from I-DEAS to NX, I can say it looks pretty promising. I have used the CMM in Native mode (no teamcenter installation, just reads out of the TDM and outputs NX files). All of what i tried so far has almost been 100% perfect, and what little things that did come up were not an issue. Also all of was i migrated was parts, assemblies and drawing of pretty prismatic parts.
