Hello,

If you have an Enterprise, Unlimited, or Developer Edition organization, you can choose which user profiles have access to the
package as part of the installation process. You can set the appropriate user and
object permissions on custom profiles as needed.


Grant access to all users Specifies the following settings on all internal custom profiles:
Object permissions—“Read,” “Create,” “Edit,” “Delete,” “View All,” and “Modify All” are all enabled
Field-level security—Set to visible and editable for all fields
Apex classes—Enabled
Visualforce pages—Enabled
App settings—Enabled
Tab settings—Determined by the package creator
Page layout settings—Determined by the package creator
Record Type settings—Determined by the package creator
Note: The Customer Portal User, Customer Portal Manager, High Volume Customer Portal, Authenticated
Website, Partner User, and standard profiles receive no access.
Select security settings Allows you to choose the usage access for all existing custom profiles in your organization. You can set each profile to have full access or no access for the new package and all its components.

Note: Depending on the type of install, you might not see this step. For example, in Group and Professional Editions,
or if the package does not contain a custom object, Salesforce skips this step and the next, giving all users full
access. Permission sets aren't included in the security options. If your package includes permission sets, assign them
after installation.

For details please refer following link:

http://ap1.salesforce.com/help/doc/en/salesforce_appexchange_install_guide.pdf