I used the wayback machine yay!
http://web.archive.org/web/200502212...=9&ForumID=132
it shows how haste works very well, here's an excerpt :
There are 4 versions of haste.
For every type of haste, only the highest percentage haste
is applied. The other stats granted by an ability are still in
effect, which is usually what skews people's perception of how
haste works.
v0 == item haste
v1 == icon haste (songs, spells, right-clicks)
v2 == ervaj line of songs type haste
v3 == vah shir / rizlona's / ranger AA type haste
v0 + v1 + v2 (equal or less then) 100 percent haste.
v3 may go over 100 percent haste. v3 doesn't only increase
the cap, it actually grants that percentage of haste as well.