Can any one please let me know when do we use list? when do we use map? when do we use set?

I'm bit confused regarding their usage.

I apologize if this has been asked before, I am yet to find an explicit answer to this question.

My (non-profit) organization uses Salesforce Enterprise Edition.  Is there an additional any cost to use force.com sites (assuming we stay within the "Enterprise Edition" limits, given in the user's guide)?  Any site we create would be public (no customer portal).

Thanks.

Hi - Apologies in advance if this has already been posted - searched but just could not find...

I'd like to confirm the current Price and Availability for Sites

Price (for Enterprise Edition)

The "Selecting the Right Salesforce Edition" does not seem upto date.

http://www.salesforce.com/uk/assets/pdf/datasheets/pdf_en_right_edition.pdf

Availability (for EMEA)

Spring '09 has it at Developer Preview and Winter '10 Release notes show it as in production which is great.

http://na1.salesforce.com/help/doc/en/salesforce_winter10_release_notes.pdf

Any dates for when this will be available? 

Regards

Paul

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