I wanted to know if there is a way to get automated notification via mail when a new SQL instance is discovered in the network?
There is no out-of-the-box solution for this one, but you can implement a windows service that keeps looking for instances endlessly, warning any interested party when a new one is found...
If you know how to program, it should not take you more than 10 min to do so...
Edit1
Turn up VS and create a new project. Select as a template "Windows Service".
Add the reference to the SMOs
Use GetDataSources() to find instances and store them on a list or whatever
Upon loop, check for new instances. new instance found? SendMail!