Rumour has it that high-flying startup StumbleUpon is in an acquisition discussions since at least last November. The talk heated up again recently with Google, AOL and eBay as potential suitors. A source with knowledge of the deal now says the company has signed a term sheet with eBay to be acquired. The price is somewhere between $40 – $75 million.

StumbleUpon lets you rate websites via a browser toolbar. When you click “Stumble!”, you will be taken to a website highly rated by other StumbleUpon users who tend to vote in a similar way as you (the person “stumbling.”). Usually, it’s something of interest to you.

So, why would eBay be interesed in something like this? Click to read the logic…