<p>Are the naming conventions similar in different languages? If not, what are the differences?</p>

Of course there are some common guidelines but there are also differences due to difference in language syntax\design.
For .NET (C#, VB, etc) I would recommend following resource:
Framework Design Guidelines
-
definitive book on .NET coding
guidelines including naming
conventions
Naming Guidelines
- guidelines from Microsoft
General Naming Conventions
- another set of MS guidelines (C#, C++, VB)