Update popup?

[placement80]

Today suddenly this thing popped up (see attached screenshot). I've been using Ubuntu for a few years, and this is the first time I've been prompted for an update, so I'm a little suspicious of it. Should I be concerned, or is this a legitimate upgrade notification?

[PatrickD-52761]

It's a legitimate notification. Ubuntu just released their 11.04 "Natty Narwhal" release. Depending on which version you're currently running, your support (life cycle) may be up. I would check http://www.ubuntu.com and find out whether you can upgrade (or if you'll run into issues).

Have a great day:)
Patrick.

[Rubi1200]

It is legitimate and you should definitely make backups and read the release notes before considering an upgrade:
https://wiki.ubuntu.com/NattyNarwhal/ReleaseNotes