[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?)