Last year at WineConf the plans for Wine 1.4 were laid out and the key hopes included animated cursors, 64-bit Gecko support, native cursor themes, AcceptEx support, Mono package integration in a similar manner to the Mozilla Gecko integration in Wine, and for the 64-bit build to pass the "make test" process. The Wine 1.4 release criteria beyond that was set to be right-to-left language support (Hebrew, Arabic, etc), X Input 2 support, USB support, and audio re-design support.
Some of the non-essential items sought after for Wine 1.4 include support for Wine add-ons, DOSBox integration, translations using PO files, static import libraries, cleaning up COM macros, and DLL registration. All of these items are mentioned on the Wine release criteria Wiki page.
AcceptEx is a Microsoft function that's needed for Warcraft III support and other games, which fortunately has long been corrected in the Wine 1.3 series. The right-to-left language support and the X Input 2.0 support have also been committed to the Wine code-base quite a while ago. For those paying attention to the recent Wine release announcements, there's been new audio support that's actively being worked on at the moment (PulseAudio support for Wine still isn't complete; the bug report).
Proper USB support for Wine 1.4 is also still missing. This support is sought after so that running Apple iTunes in Wine would then be able to sync with an iPod/iPhone, among other purposes, but there hasn't been much activity in its bug report.
There's a total of 33 open bugs right now that have a target milestone of Wine 1.4.0 (found here). The other items range from Touchpad mouse cursor flickers to other keyboard/mouse input issues, memory leaks, and various sound problems. Wine 1.4 was originally expected for release in 2011, but with only two months left to the year, chances are it will be a 2012 release.
For reference it was about two years between the Wine 1.0 and Wine 1.2 releases. Wine 1.2 came roughly one year later. Prior to the release of Wine 1.2 there were over 40 Wine 1.1.x development releases. Fortunately for many Wine users, the bi-weekly development builds tend to be stable enough for day-to-day use.