The last nightly image is hrev44584, but we are now at hrev 44600. There are a lot of changes that need to be tested.
As we are in a release cycle, most of the nightly images have been suspended.
On http://www.haiku-files.org/haiku/development/ the hrevr1alpha4-XXXXXX images are the @alpha-* builds from the r1alpha4 release branch. These are the ones to test, as that is what R1 alpha 4 will be.
To note: even though the hrev44579, hrev44581, and hrev44584 images appear newer than hrevr1alpha4-44580. However, that is not the case. The master and r1alpha4 git branches have their own separate tag numbers, and there was a delay in updating the nightly image builder script to the r1alpha4 branch.
OK, posting from the latest r1a4image running in QEMU on r1a3. a Haiku within a Haiku so to speak.