I noticed that too. The necessary CAs are actually installed on Lucid by default though (you just have to tell openssl where to look). Incidentally, wget works fine (without --no-check-certificate):

$ openssl s_client -CApath /etc/ssl/certs -connect cas.ucdavis.edu:443
CONNECTED(00000003)
depth=1 /C=US/O=Equifax/OU=Equifax Secure Certificate Authority
verify return:1
depth=0 /C=US/ST=California/L=Davis/O=University of California Davis/OU=IET-IR/CN=cas.ucdavis.edu
verify return:1
---
Certificate chain
 0 s:/C=US/ST=California/L=Davis/O=University of California Davis/OU=IET-IR/CN=cas.ucdavis.edu
   i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
 1 s:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
   i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=/C=US/ST=California/L=Davis/O=University of California Davis/OU=IET-IR/CN=cas.ucdavis.edu
issuer=/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
---
No client certificate CA names sent
---
SSL handshake has read 2147 bytes and written 276 bytes
---
New, TLSv1/SSLv3, Cipher is EDH-RSA-DES-CBC3-SHA
Server public key is 1024 bit
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : EDH-RSA-DES-CBC3-SHA
    Session-ID: 4C116E5221F8596C7B1BE3E4443D427A6234FCE19A12F6E869C3F0C536715A7D
    Session-ID-ctx: 
    Master-Key: C52784FE43D5156FDB3A81670E1BF87585502BC5C38EAE214F2C93285743BB8B050B8B111751A7B16A3784159B6444B3
    Key-Arg   : None
    Start Time: 1276210770
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)
---
HEAD / HTTP/1.0

HTTP/1.1 302 Moved Temporarily
Server: Apache-Coyote/1.1
Location: https://casweb3.ucdavis.edu:8443/login
Content-Type: text/html;charset=ISO-8859-1
Content-Length: 0
Date: Thu, 10 Jun 2010 22:59:33 GMT
Connection: close

closed
$ wget https://cas.ucdavis.edu
--2010-06-10 16:01:53--  https://cas.ucdavis.edu/
Resolving cas.ucdavis.edu... 169.237.104.82
Connecting to cas.ucdavis.edu|169.237.104.82|:443... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: https://cas.ucdavis.edu/login [following]
--2010-06-10 16:01:53--  https://cas.ucdavis.edu/login
Connecting to cas.ucdavis.edu|169.237.104.82|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 4796 (4.7K) [text/html]
Saving to: `login'

100%[=========================================================================================================>] 4,796       --.-K/s   in 0s      

2010-06-10 16:01:53 (204 MB/s) - `login' saved [4796/4796]
$