(If SQL2008 is the same as SQL2005 in this regard, and I expect it is,...)

Don't forget that even if my default schema is DBO-- if I execute the following 2 queries, they will NOT use the same cached execution plan.

...They may come up with identical EPs, but they will both be generated.

SELECT (some columns) FROM SomeTable WHERE (some condition)

SELECT (some columns) FROM DBO.SomeTable WHERE (some condition)

... and the following query won't reuse the EP from the first either...

SELECT (some columns) FROM SomeTable WHERE (some condition)