Miranda is beginning to fully support Unicode.
Here are some questions I (and I have heard other people) ask:
Does my plugin need to be built using Unicode to work with the new core?[]
No, not necessarily. Unicode symbols will diplay as '?????' for plugins that do not support it. Compiling for Unicode will give wider compatibility for current operating systems.
What about the database?[]
To write to the database (and indeed for other parts of Miranda) there are special Unicode-aware services. You can usually tell these by the presence of a 'W' at the end of a function name.
Should I stop releasing Non-Unicode builds of my plugin?[]
No, not yet! Some people on older operating systems may have difficulty with Unicode builds. These can often (but not always) be worked around however.
Windows 95,98,Me do not natively support Unicode.