Recent Q1 reports indicate that LinkedIn saw a 91% increase in premium subscriptions last year, leading to $37.9 million in revenues for the first quarter.This figure, of course, does not account for all of the company's revenues as LinkedIn has a hybrid subscription-advertising Model. Advertising brought in $48 million, accounting for 26% of the company's total revenues. Yet, the 91% growth in subscriptions noted above is promising, as subscriptions now take up 20% of the revenue pie. Interesti...