The following bug has been logged online:
Bug reference: 6122
Logged by: Mike Holywell
Email address: mike(at)segment8(dot)co(dot)uk
PostgreSQL version: 9.0.4
Operating system: Mac OSX 10.7 (Lion)
Description: Installation fails: "database cluster initialisation
failed"
Details:
On a fresh install of Lion (11A511) installing Postgres 9.0.4 fails
Problem running post-install step
installation may not
complete correctly
The database cluster initialisation failed
This has been reported on other blogs eg
http://seeboriscode.blogspot.com/2011/06/osx-107-lion-postgres-installation.
html
I've had a similar(?) problem with the dscl command not creating the user
under earlier Lion Betas