From Miranda Forums:

GaduGadu: Edit

Supports: Edit

Search/Add/Delete contacts
Export/Import contacts to/from server/file
Changing own info
Ignoring contacts
Sending/receiving files
Sending/receiving images
Custom online/away/offline messages
Joining/leaving/ignoring conferences(chats)
'Friends only' mode
Manual server assign
Creating/deleting accounts
SSL connections (not supported by GG servers though)

Doesn't support: Edit

Sending SMS messages (available through other plugins though)
Telephoning