Given the obsession with all things Twitter, this has been one of the most anticipated and hotly discussed fundings in a while: Om reports that after much jostling, the micro-blogging/messaging company has nailed down a $15 million second round, bringing its total raise to around $20 million. The pre-money valuation is said to be $80 million. Past backer USV participated as well as an unspecified lead investor.

Pretty much every discussion about Twitter has to revolve around (at least) one of three things: reliability, mainstream adoption and business model. The new round comes amidst a particularly bad stretch at the company, which has been suffering blackouts on a daily basis as of late. While there’s hope that the new funding could help solve some of these woes, it’s not clear that the problem is something that will just go away with more money thrown at it. A recent post on the company’s blog basically states that the crux of the problem is unknown. As it wrestles with this issue the company has had some turnover among its key engineers. Still, it’s not obvious what long-term effects Twitter’s downtime will have on the company. Faithful customers are obviously frustrated by it, but not necessarily to the point where they’ll stop using it. Growth, meanwhile, has been off the chart.

Of course the business model remains a bit of a mystery, and perhaps more than anything, this new round is about buying the company time to figure that out without resorting to something cheap and obvious like banner ads across the site.

• Twitter’s Summer Funding: $4.8 Million of a $5.4 Million Round
• Twitter Raises First Round From Union Square Ventures, Angels