Today, the company is unveiling a new mobile service at m.youtube.com that it said will carry most of YouTube’s catalog, or tens of millions of videos. The site will also have personalization and community features that it lacked before, so users will be able to log in and subscribe to certain channels or have easy access to their favorite videos. And they’ll be able to upload videos directly from their mobile devices.

Watching videos on mobile phones remains a niche activity. YouTube said its mobile site will be accessible from devices that are capable of streaming video and that run on 3G networks. According to the company, that’s about 100 million devices worldwide, a small fraction of the more than 3 billion cell phones in use around the world. What’s more, many of those devices, especially overseas, run on limited data plans, so watching videos can prove expensive, as YouTube notes on its mobile Web site: “YouTube Mobile is a data intensive application. We highly recommend that you upgrade to an unlimited data plan with your mobile service provider to avoid additional charges.”