Multiple sources out of Silicon Valley are indicating that Yahoo is in serious talks to acquire Tumblr for as much as $1 billion. First reported from the technology news site All Things D, the acquisition of the social blogging service would mean a quick infusion of youth for Yahoo — a priceless commodity for the struggling Internet company, one viewed by advertisers as having grown stale over the years. For Marissa Mayer, installed as Yahoo CEO last summer, the acquisition would represent her biggest deal to date. And while fraught with risk, the acquisition could potentially offer big dividends: according to All Things D, Tumblr has a reported valuation of $800 million. The site has nearly 108 million blogs containing over 50 billion posts, drawing 64 million unique visitors and nearly 5 billion pageviews in the last month. Talks are said to be “fluid” between the two companies, with a possible deal being announced as early as this weekend.