We should probably also have a notion of dependencies:
<dependencies> <dependency>Semantic MediaWiki</dependency> </dependencies> This will be important for extensions like the extensions which use SMW, ones which use DPL, or things like the BizzWiki extensions or other ones which require things like the SimpleRegex classes, or other extensions meant to simplify functionality for other extensions. Trying to install those without their dependencies would lead to fatal php errors.
It would also be nice if we could list PHP dependencies, that could be checked by some core code, rather than by each extension. For instance, quite a few people have issues with the LDAP Authentication plugin becuase their PHP doesn't have LDAP support either compiled in, or included via a module.
V/r,
Ryan Lane