John's plan above is pretty solid. I'd note that $1,000/mo is the payment on his current mortgage, and may not be the payment once he's refinanced. Remember to consider the cost of maintenance and updates, too. I generally recommend setting aside 2% of the property's market value for that, so in this case $4,300/year. If your friend will make $600/mo after mortgage and condo fees, that's $7,200/yr. $4,300 gets reinvested in maintaining the unit, and he takes $2,900 profit annually. Plus the property appreciates, and his mortgage is paid by someone else.
If you figure he leaves 20% of the value in when he refinances, or $43,000, his ROI is 6.7% (2,900/43,000). To determine if this is the BEST plan of action, you'd have to evaluate other investment opportunities and their ROIs. I would say, though, considering the transaction costs of buying and selling real estate, keeping something he already owns as a rental property will generally be lucrative compared to buying a new investment property.
If this is your friend's first foray into real estate investing, he may want to rent it out without refinancing, and see how he likes having a rental property. If he finds he can do it well, then he can refinance and use that cash to buy more properties.