Lenny's Debian Installer won't support Sparc32 :
Therefore, Debian support for Sparc-32 should be dropped when Etch support is dropped, i.e around S2-2009 (according to etch current roadmap).
The Keep Sparc32 Alive Page
The main problem with sparc32 is that there are no Linux kernel maintainers. This problem absolutely needs to be addressed if there should be continued support for Debian GNU/Linux on 32 bit Sparc machines.
Since the kernel is not Debian specific, searching for other Sparc32 linux distributions might be interesting, too. (There was a page on Wikipedia for a few days, but it was deleted.)