> If not, then why on Earth is there a release of version
> 1.4.3 just 4 days before the 1.5 release?

Hm, in some sense that might look like bad timing.  However, as
others have pointed out, the two releases serve slightly different
user groups.

I'll just also note that the 1.4.3 release announcement contained
this passage:

  NetBSD 1.4.3 is a patch release of the 1.4 release branch.  The 1.5
  release branch will have its major release, NetBSD 1.5, shortly.

...so it should ideally not come as a big surprise that the 1.5
release would follow within a rather short time.

Best regards,

- H=E5vard