Per the 10-K, Prosper had $4.3million in cash on December 31st, 2010 and their average burn rate for 2010 was ~$875,000/month.
If everything were to stay the same, Prosper would be running out of money around the end of May or beginning of June in 2011.
If they are going to get a VC infusion, they better get it within the next 1.5-2 months.