nashNET have released an alpha version of VSTrack, which is apparently the ultimate union of sequencing and tracking.

VSTrack is a VSTi plug-in that provides a tracker interface, based on Impulse Tracker II, to the user. Unlike normal VSTis which simply take MIDI input, VSTrack's editor window is a tracker interface, which takes on the role of the 'music sequencer' - synthesizing both music and sound.