I live in Florida. I am on a month to monthh lease. When I leased the apt I gave landlord last months rent. I gave 30 days notice to vacate in June, paid the June rent and vacated on 30th of June.
Landlord says I'm not entitled to unused last months rent.

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Why does he say that? Do you have the receipt for the payment that indicates it last month's rent or a security deposit or what? Also since its only June 25th did this happen a year ago?

I got ahead of myself, I will move out by June 30, 2009. Yes, I do have a receipt for the last months rent. I also have a receipt for a separate security deposit.
(sorry about the piggybacking)

OK, So in Florida the landlord has 30 days to submit a statement of how the security deposit was used. I would think this applies to last month's rent as well. He definitely can't keep rent he hasn't earned.

So I would send him a letter when you vacate informing him of your new address. In that letter make a statement that, since you paid for your last month rather than use the last month's rent you paid when you moved in you will expect the return of that plus your security within 30 days.

If you don't get it, then you will have to take him to court.