Every time the mongo shell is started it results in a copy of .dbshell in the current working directory. This can lead to multiple copies of .dbshell in different directories. It should probably create a single copy of .dbshell in the user's home directory.

To reproduce:

C:\test>dir
Volume in drive C is OS
Volume Serial Number is 2E9C-358E

Directory of C:\test

09/20/2011 02:49 PM <DIR> .
09/20/2011 02:49 PM <DIR> ..
0 File(s) 0 bytes
2 Dir(s) 103,552,892,928 bytes free

C:\test>\mongodb\mongodb-win32-x86_64-2.0.0\bin\mongo.exe
MongoDB shell version: 2.0.0
connecting to: test
>
C:\test>dir
Volume in drive C is OS
Volume Serial Number is 2E9C-358E

Directory of C:\test

09/20/2011 02:49 PM <DIR> .
09/20/2011 02:49 PM <DIR> ..
09/20/2011 02:49 PM 0 .dbshell
1 File(s) 0 bytes
2 Dir(s) 103,552,892,928 bytes free

C:\test>mkdir subdir

C:\test>cd subdir

C:\test\subdir>dir
Volume in drive C is OS
Volume Serial Number is 2E9C-358E

Directory of C:\test\subdir

09/20/2011 02:49 PM <DIR> .
09/20/2011 02:49 PM <DIR> ..
0 File(s) 0 bytes
2 Dir(s) 103,552,892,928 bytes free

C:\test\subdir>\mongodb\mongodb-win32-x86_64-2.0.0\bin\mongo.exe
MongoDB shell version: 2.0.0
connecting to: test
>
C:\test\subdir>dir
Volume in drive C is OS
Volume Serial Number is 2E9C-358E

Directory of C:\test\subdir

09/20/2011 02:49 PM <DIR> .
09/20/2011 02:49 PM <DIR> ..
09/20/2011 02:49 PM 0 .dbshell
1 File(s) 0 bytes
2 Dir(s) 103,552,892,928 bytes free

C:\test\subdir>