Just in case you haven't already heard, Dynamics NAV 5.1 has been canned. Instead, it will be called Dynamics NAV 6.0 and will be delayed until Q4 2008.
Why? My guess is they just couldn't finish it in time and so, rather than delay it again, they killed it. Now before I start ranting, I have to admit this decision has positive aspects. Releasing an unstable 5.1 product would have shown a lack of vision surpassed only by Wayne Barnes' recent performance in the All Blacks-France World Cup Quarter Final.
The Dynamics NAV 6.0 product (previously known as 5.1, previously known as 5.0) promises to be something special and it is important that it works.