Ok, I just had to share this with you guys-

A company named Nuton have released a VST effect that converts audio from your instrument (ie guitar) to MIDI to be routed into a VST instrument.

I've used it with my guitar and must note that the instrument has to be tuned perfect! It is also mono, not poly so you cant play chords, if you do the loudest note will only come through. It works by determining the fundemental frequency of the note that you are playing... Note that latency may be an issue to some...

Anyway you can get a 30 day trial here-
http://nuton.ca/

Enjoy folks!

Samplitude has also a tool called "Tuner" that gives you the approximated pitch of the track while you are monitoring. I suppose that it's only right when the track is monophonic but some times it can be very useful.