This keyboard combination has been removed from SQL 2008. You can still get to the functionality by selecting Query >> Specify Values for Template Parameters...
This is quite confusing because most templates still reference the keyboard combo. (The menu item above even references it!!)
Unfortunately, we can't "restore" the Ctrl-Shift-M command. SQL Mgmt Studio doesn't allow adding new shortcuts. Only "query" shortcuts (Options >> Environment >> Keyboard).
The easiest way to resolve this is to just learn the new keyboard sequence: Alt >> Q >> S
Here's a confirmation by Mark Han on the MS Online Community Support team:
In order to resolve the issue, I
would like to explain the following
A) I have re-produce the issue and compare it with SQL Server 2005
Management Studio. It is confirmed that the "Ctrl-Shift-M "
shortcut key
does not exist in SQL Server 2008 Management Studio. If you have
concerns
on that, please send us a feedback via the
address(https://connect.microsoft.com/sql).
Besides I'm consulting with our
dev team with the issue; if anything updates, we will public[ize] it.
B) Ctrl-Shift-M is used to replace template parameters, we also
can open
Specify Values for Template Parameters manually
1) On the Query menu, click Specify Values for Template
Parameters.
2) In the Specify Values for Template Parameters dialog box, the
Values column contains suggested value for the
parameter (Database Name in the example above). Accept the
value
or replace it with a new value, and then click OK
to close the Replace Template Parameters dialog box and
modify
the script in the query editor.
Hope this helped!
Joe Cogan
Solutions Architect
TEKsystems Global Services