I think this is a smart move. Zendesk already figured out that Uservoice alike "feature request management" is a must in a help desk system and they added this feature to Zendesk couple of months ago.
We were using Uservoice and Zendesk, ditched Uservoice as soon as Zendesk started to provide a similar feature to avoid having 2 systems.
Edit: Pricing is unusually low for Zendesk, I assume they'll increase that later on.
And we added ZenDesk even though we use UserVoice! But it is a problem because we get people asking support questions on UserVoice. It would be nice to have one system; we would consider switching as well if UV FS turns out to be nice. I'll give it a few months to bake though :)
You should try us out now! We've been using this system for all our own support for many many months and we've had 40 beta testers banging on it. Plus we have a 30-day free trial so you can play around. :)
We were using Uservoice and Zendesk, ditched Uservoice as soon as Zendesk started to provide a similar feature to avoid having 2 systems.
Edit: Pricing is unusually low for Zendesk, I assume they'll increase that later on.