Really depends on where you currently work / are seeking work. Knowing more than one language (or development framework) can definately look good on a CV and show that you are capable of being flexible. However having the depth of knowledge / experience that comes from spending time developing with even a single language can be far more valuable.
As Nerseus posted above, the language quickly stops becoming the issue. Knowing how to write robost, usable (and re-usable), stable code in any language; the ability to follow standards, design (or write code that works with existing ones) application / frameworks; Having an understanding of common design patterns and more importantly know when and why they should be used. These skills can be learned independant of any language but they need to be learned and the best way is spend time using a language to the full.
Being able to prove you can develop all the way from initial idea to completed application and hence experience all stages of the design process (including testing and final polishing) will be far more useful than being able to demonstrate a basic knowledge of several languages but no real depth of knowledge in any