Twitter, the popular microblogging service, has raised a new venture round of $35 million. Benchmark Capital and Institutional Venture Partners led the investment. The news follows reports last month that Twitter was raising a new $20+ million round at a $250 million valuation. No word yet on whether Amazon.com founder Jeff Bezos, an early investor in Twitter, took part in the new funding.

In a blog post today, Twitter co-founder Biz Stone said the company wasn't actively seeking more capital but decided to accept a "very attractive offer." Addressing concerns about Twitter's lack of a revenue model, Stone writes:

"We are now positioned extremely well to support the accelerating growth of our service, further enable the robust ecosystem sprouting up around Twitter, and yes, to begin building revenue-generating products. Throughout this year and beyond, our small team will grow much bigger to meet the challenges and opportunities ahead."

There's been a lot of speculation recently about how Twitter will try to generate revenue, including charging for corporate accounts.

Twitter didn't specify the amount of new funding, but a spokeswoman for Institutional Venture Partners confirmed the round totaled $35 million. I sent an email to Bezos Expeditions, Jeff Bezos' personal investment vehicle, to find out if the Amazon founder took part.