I recently learnt that eTiny, OpenERP’s web server, is actually caching pages when in “production” mode (this mode can be changed in the configuration file which is /etc/etiny-server.cfg if you followed the documentation here).
This means that installing some modules may not have a direct visual effect if you have already seen a page before altering it with the module installation.
To avoid caching, you can either change the eTiny server mode in /etc/etiny-server.cfg (to “development” I guess), or simply restart the eTiny server. This will erase the cache.
Of course, none of these methods is actually acceptable once the server is in production, but at least there is a way… (I suppose a way to clean the cache via a script while the server is running would be good).