- The fact that -current is much better than 1.5.x on
             sparc64 is not news to most on this list, but we really
             ought to mention this on the webpage. Had I just stuck
             with 1.5.1 on the box I would never have considered
             putting it to real use. -current changed that.

can you handle this side of things?  :-)
   
           - Found the odd compiler codegen and LP64_LE issue in pkgsrc
             but its happily compiled up and run a bunch of applications
             including apache, gimp, ghostscript, xv, perl.

avoiding -O2 can often remove these problems.  others require source
modifications... also pkgsrc has a bunch of fixes already.  you should
probably get patches into pkgsrc for any problems you find.
   
           - The only real issue I've hit is that there seems to be
             a problem compiling C++. A 'hello world' program will
             fail at runtime with:
   /usr/lib/libstdc++.so.4: Undefined symbol "" (reloc type = 54, symnum = 18)
             gcc -v reports 2.95.3. Was this toolchain used to build
             the snapshot? (ie: groff)

groff doesn't use libstdc++, but this is basically a known issue.  C++
in general doesn't work on sparc64 though some applications that only
use a small subset of C++ (like groff) will work just ine.
   
           - Its a 256MB machine but it always seems to have over
             100MB free, I would have expected the UBC to take care
             of that?

this is probably because the default number of vnodes is too small.
my ultra1 with 256MB of ram currently says:

There are 22598 pages for vnode page cache using 180784 kBytes of memory.

but i have:

	options         NVNODE=15000

in my kernel config, which allows it to use more vnodes and thus to
cache more ram for files.  (as i understand it, pages in the page
cache need to have active vnodes.)