No, it is not. activeCollab 1.0 does not have localization support, but we are working on it for v1.1*

* Disclaimer: information subject to change, base your purchase decision on features currently available!

We completely understand that your clients may not speak English, but currently you cannot localize activeCollab interface.

activeCollab 1.0 did not inherit that feature from v0.7. v1.0 haven't inherited much from 0.7 version- system was rewritten completely to include all the new features and work properly on PHP4. It's a new script.

You can't localize the app per say, but you can definitely have a translated interface (in french in my case) if you do like I did, which is translate the view files but it takes around 3 days to do so and some remaining strings are not translated.

It's enough for me at the moment, and my clients are happy with it :)

Check this thread to see how I did it
Beware that as Ilija says "hacked views are not upgradable".