Nearly a year after its launch, the “new” Twitter interface will roll out to all users this week — whether they want it or not.

The company tweeted this afternoon with a warning to those who’re still using the old Twitter interface:

If you’re currently using Old Twitter, we want to let you know that you’ll be upgraded to New Twitter this week. twitter.com/newtwitter

Twitter announced the new interface all the way back on September 14, 2010. It was (and is) a completely new way of presenting content, with two columns of information, images and other content embedded into Twitter.com (and viewable without leaving the site) and several other changes.

All this time, Twitter has let users continue to use the “old” Twitter if they preferred, and many have done that. Ready or not, those folks will have to get used to new Twitter starting sometime this week.

On a semi-related note, Twitter also tweeted today about its HTML5 version of Twitter.com for iPad users, saying that’ll roll out “over the next week or so.”