Since the first quarter just ended, Twitter’s PR team decided to tweet updates stats regarding the state of Twitter today. Of them, the biggest is that Twitter saw a 41 percent increase in tweets per day (and a 38 percent increase in the U.S.) for the quarter.

But the biggest single number isn’t pertaining to Q1 at all, it’s live. Twitter is now seeing 155 million tweets a day. That’s up from just 55 million a year ago, the company says. It’s also up from 140 million just a few weeks ago.

The full stats:

Been playing with numbers. Big Q1 for Twitter… 41% increase in Tweets per day. 38% increase in Tweets per day in US. [1/5]—
Twitter Comms (@twitterglobalpr) April 06, 2011

There was a 52% increase in monthly Twitter account signups from December to March — with 57% increase in the US. [2/5]—
Twitter Comms (@twitterglobalpr) April 06, 2011

Mobile growth on Twitter was big. There was a 50% increase in monthly unique mobile signups. [3/5]—
Twitter Comms (@twitterglobalpr) April 06, 2011

Q1 increase in Twitter app monthly users – 104% Android, 72% iPad, 55% iPhone, 51% Blackberry [4/5]—
Twitter Comms (@twitterglobalpr) April 06, 2011

Oh and – not a Q1 stat – but noticed that we're now at 155 million Tweets per day, up from 55 million at this time last year. [5/5]—
Twitter Comms (@twitterglobalpr) April 06, 2011