There is a guide for updating your MINIX system to 'current' with CVS (a 'source upgrade'): tracking 'current'.
A recent change to packman makes it aware of Minix versions, which is important for backwards compatability if something in the Minix ABI changes.
(This only happens as a last resort though.) The new structure knows about Minix versions, architectures, and beta and nonbeta ports. The structure is backwards-compatible with the latest official release (3.1.2a).
To take advantage of this feature before the next release, you can do a source upgrade and obtain packages that have been recompiled to solve some problems due to ABI changes.
Recent new port highlights are ghostscript, ghostview, and libXaw3d. They're on the software page under the beta section, and available from packman and easypack.
The source snapshot has disappeared in favour of using CVS.