Postgresql – Recover PostgreSQL database from WAL errors on startup

I'm trying to set up an OpenStreetMap server on an Ubuntu 12.04 machine using the Ubuntu packages listed at switch2osm.org. I initially installed and set up everything using a Northeast US-only map extract, but now I want to install the entire planet of maps. I downloaded planet-latest.osm.bz2 and ran osm2pgsql --slim -C 60000 planet-latest.osm.bz2 as a user with write permission to the database; this was the same command that worked to install us-northeast.osm.pbf earlier. I came back the next day to find this command appeared to finish successfully, but for some reason the rendering daemon wasn't generating new tiles from the new data. I tried restarting renderd, and when that had no effect I tried restarting the PostgreSQL server with sudo /etc/init.d/postgresql restart. However, server startup failed with the following errors in the log:

2012-07-13 18:54:59 UTC WARNING:  page 1525147 of relation base/16385/477861 was uninitialized
2012-07-13 18:54:59 UTC WARNING:  page 2247965 of relation base/16385/477861 was uninitialized
...500 more lines like this...
2012-07-13 18:54:59 UTC WARNING:  page 2262926 of relation base/16385/477861 was uninitialized
2012-07-13 18:54:59 UTC PANIC:  WAL contains references to invalid pages
2012-07-13 18:55:00 UTC LOG:  startup process (PID 22826) was terminated by signal 6: Aborted

(Pastebin of entire log here).

There isn't much information on these kinds of errors on the Internet, but from what I can find it seems to mean that either my indexes are corrupted or my Write-Ahead-Log is. The only way to fix corrupted indexes, though, is to start the database in single-user mode and rebuild them, and I can't even do that because I get the same fatal errors even when I start in single-user mode with indexing disabled.

Is there any way for me to delete the Write-Ahead Log and force the server to start up "from scratch", or a fix for this kind of corruption that doesn't require first starting the database successfully?

Alternatively, is there a way for me to delete the database and just re-import all the planet data, given that I can't start the server to execute the DROP DATABASE command?

UPDATE:

Following Craig Ringer's suggestion, I went and looked through the database logs from before the WAL errors started occurring to see if I could find any suspicious behavior. In the log from immediately before the first instance of WAL errors, I found these suspicious-looking lines:

2012-07-13 00:20:51 UTC LOG:  received fast shutdown request
2012-07-13 00:20:51 UTC LOG:  aborting any active transactions
2012-07-13 00:20:51 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:51 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:51 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:51 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:54 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:54 UTC STATEMENT:  CREATE TABLE planet_osm_polygon_tmp AS SELECT * 
FROM planet_osm_polygon ORDER BY way;

2012-07-13 00:20:55 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:55 UTC STATEMENT:  CREATE INDEX planet_osm_ways_nodes ON planet_osm_ways 
USING gin (nodes)  WITH (FASTUPDATE=OFF);

2012-07-13 00:20:57 UTC FATAL:  terminating connection due to administrator command
2012-07-13 00:20:57 UTC STATEMENT:  CREATE TABLE planet_osm_line_tmp AS SELECT * 
FROM planet_osm_line ORDER BY way;

2012-07-13 00:21:51 UTC LOG:  received immediate shutdown request
2012-07-13 00:21:52 UTC WARNING:  terminating connection because of crash of another
server process
2012-07-13 00:21:52 UTC DETAIL:  The postmaster has commanded this server process 
to roll back the current transaction and exit, because another server process 
exited abnormally and possibly corrupted shared memory.
2012-07-13 00:21:52 UTC HINT:  In a moment you should be able to reconnect to the 
database and repeat your command.
2012-07-13 00:21:52 UTC LOG:  could not send data to client: Broken pipe
2012-07-13 00:21:58 UTC WARNING:  terminating connection because of crash of another 
server process
2012-07-13 00:21:58 UTC DETAIL:  The postmaster has commanded this server process 
to roll back the current transaction and exit, because another server process
exited abnormally and possibly corrupted shared memory.
2012-07-13 00:21:58 UTC HINT:  In a moment you should be able to reconnect to the
 database and repeat your command.
2012-07-13 00:21:58 UTC LOG:  could not send data to client: Broken pipe

(Pastebin of the entire log is here)

When it says "terminating connection due to administrator command," I assume that was my command to restart the database server. But it looks like the shutdown somehow failed horribly, resulting in corruption of shared memory. This doesn't make sense, because I restarted it "cleanly," using the /etc/init.d/postgres restart script, not an abrupt kill or manually logging in as postgres. Am I interpreting this log incorrectly? Or is there actually a problem with using /etc/init.d/postgres restart to restart a PostgreSQL server?

(Please note, since my question was moved to Database Admin, where I'm a "new user," I no longer have the ability to upvote your answers. This doesn't mean I don't appreciate the help).