Ask Slashdot: Is there an Open PKI initiative?

Psarchasm asks: "Recently I've begun looking into PKIs (Public Key Infrastructures). And with all the pros I've found (desktop security, IPSec/VPN, digital signatures, running our own Certificate Authority - I seem to have run into a rather unfortunate con. I can't find an Open Source PKI initiative. Is there any work being done on an Open Source CA server? How about a PGP Key Server? Would it be possible to implement something semi-secure in a closed environment with a combination of PHP3/SQL/LDAP for a PGP Key Server?"