[7.3] can't connect with SSL

I just upgraded my server from 7.2.1 to 7.3 last night, and can no longer
connect over SSL (unencrypted connections still work ok, but I really need
SSL). I get the following error messages when I try to connect:

psql (PostgreSQL client) 7.2.1
psql: could not establish SSL connection: No SSL error reported

serverlog:
FATAL: failed to initialize SSL connection: wrong version number

I have the same version of openssl on both the client and server
machines. Both are running Debian 3.0, with these libs:
- libssl-dev 0.9.6c-2.woody SSL development libraries, header files
- libssl0.9.6 0.9.6c-2.woody SSL shared libraries
- openssl 0.9.6c-2.woody Secure Socket Layer (SSL) binary and related

My server configuration is like so (everything else is default):

pg_hba.conf:
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
local all all crypt
hostssl all all 0.0.0.0 0.0.0.0 md5

postgresql.conf:
tcpip_socket = true
ssl = true

It was of course also configured for use with SSL:
/configure --with-perl --with-openssl=/usr/include/openssl
checking for SSL_library_init in -lssl... yes
checking openssl/ssl.h usability... yes
checking openssl/ssl.h presence... yes
checking for openssl/ssl.h... yes
checking openssl/err.h usability... yes
checking openssl/err.h presence... yes
checking for openssl/err.h... yes

Now it sounds to me like this is an SSL handshake problem, but I don't
see why, because I have exactly the same version of openssl on both the
client and server machines. On my client machine, I still have v7.2.1
of 'psql' (the client binary) as that's what came bundled with my
operating system. I'm fairly certain that's not what's causing the
problem though (or is it?)