Two years ago: March 5, 2010, Instagram raised $500,000 in seed funding.
One year ago: February 2, 2011, Instagram raised $7 million on an estimated valuation of $20+ million.
One month ago: March 9, 2012, Instagram raised $40 million on a valuation of $500 million.
Last week: April 6, 2012, Instagram raised another $50 million on the same valuation of $500 million.
Today: Sold for $1 billion.