Hi,
we are using JW Player for many of our customers, and have completely dropped the idea of making a custom player in favor of using JW which works GREAT. We just love it :-D With plugins idea it got more extensible. Even some big CDN's have realized they have to support JW, since majority of users are using it.
We have several issues however. I am not sure do you even plan on working on them, but i thought I should mention them, perhaps other people would like this too :)
- Live / VoD switching - it would be great if playlist would support switching between live and prerecorded content, so we can push commercials and jingles to live viewers. This is our top most wanted feature. I saw the "streamer" var coming to playlists in JW 4.3 - did I understand well that this will resolve this problem?
- Dynamic bandwith switching (as advertised by adobe for fms3.5 and mentioned in another thread)
- DVR functionality from adobe fms3.5 - replay in live stream - this would be really great
- More great plugins :-d
regards and thank you for your wonderful player!
Could you give us a hint if any of these things are planned and for when?

The live/vod switch should indeed be possible with the "streamer" flashvar in 4.3. Note that 4.3 is as good as done and you can download it from the wiki.
DVR / and BW switching are indeed items that are on the list. I just got a copy of FMS 3.5 and can do some first testing with these new features. The 4.4 should have the switching implemented.
And more plugins are on the way!