Dan's analysis is good. It's true: You're buying it for $300 a month.
My "gut" way of looking at it is a bit different, but still . . . It's costing you $300 a month. Leaving aside any tax benefits (depreciation, etc., as well as the ability to deduct your losses from your income--check with an accountant for details), that's $300 a month, or $3,600 a year. You estimate that if you sell now, you'll lose $15,000-$20,000. The break-even point is at about 5 years--in 5 years, at the current rate, you'll lose about $18,000. That's assuming rents don't go up, and that the condo fee doesn't go up. Both probably will rise some. Recognize, too, that you're paying down on the mortgage, so you really are building up some equity.
Will the condo increase in value by $18,000 in 5 or fewer years? If so, it makes sense to hold on to it. Otherwise, no. I'm guessing, as John did, that you think it'll currently sell for about $60,000. If that's the case, then you'll need about 5% annual appreciation to get back to $80,000. Again, a bit less since in 5 years you'll owe less than $80,000.
Is 5% appreciation reasonable? Over the long term, it is. But this is a really unpredictable market. If I had to guess--and hopefully avoiding "irrational exuberance"--property values probably will bounce back. Slowly for a couple of years, then sharply after that. But that's only a guess. So, it's really kind of a close call.
I'm a bit more optimistic than John that it'll take until 2020. Still, he could be right.
A few other comments: You might be able to boost your income a bit by offering the property as a lease-option. But use realistic numbers.
And if you sell the Florida property as a short sale, you'll likely damage your credit to such an extent that you wouldn't be able to buy a better home in California for a while.
Finally, it really depends on your comfort level. Both your financial comfort level in spending $300 a month on the Florida property and on your comfort level with your current accommodations in California. If you've got a decent place in California--you're reasonably content there--and the $300, while unpleasant, is manageable--that's one scenario. But if you're living in a rat-infested falling-down home on the bad side of town, that's another.
Sorry for the lack of a definitive answer. Still, I hope that helps.