String "Aggregates" Solution

Even though I promised to update a solution to a problem,  I failed to do so for a long time.

Here is the problem

If you need to get the sum of salary by department we may be able to use Sum and group by clauses in a single select statement to get it done.  But if you have a situation where you need to give a comma separated string of employees for each department, how will you handle it?
Consider these tables:

Department Table

DepartmentID	DepartmentName
1	Sales
2	IT
3	Finance

Employee Table

EmployeeID	DepartmentID	EmployeeName
1	1	Sales Person 1
2	1	Sales Person 2
3	2	Developer 1
4	2	Developer 2
5	2	DBA 1

Now you want the results like this:

DepartmentName	EmployeeList
Sales	Sales Person 1, Sales Person 2
IT	Developer 1, Developer 2, DBA
Finance	NULL

Here is the code for yesterday's Scenario:
create table #Department
(
DepartmentID int not null primary key clustered,
DepartmentName varchar(10) not null
)

create table #Employee
(
EmployeeID int not null identity primary key clustered,
DepartmentID int,
EmployeeName varchar(100)
)


insert #Department values(1, 'Sales'), (2, 'IT'), (3, 'Finance')
insert #Employee values (1, 'Sales Person1'), (1, 'Sales Person 2'), (2, 'Developer 1'), (2, 'Developer 2'),(2, 'DBA')