The plus sign is the same as the ampersand (&). It concatenates two strings together. It is a Basic term and has nothing specific to do with 2010.

"yadda" + "blah"

is the same as

"yadda" & "blah"

BOTH = "yaddablah"

Now it MAY be true that in 2010 VBA no longer recognizes that + and & are the same. I do not know. But in WordBasic (old,old, old) the plus sign was commonly used. Certainly up to 2003 VBA did not care if you used + or &, it was happy with both, or either.