Google Scholar now sports a new "Get at CISTI" link to allow the purchase of documents via CISTI Discover for anyone using scholar.google.ca, or accessing Google Scholar from Canada. The link only appears where the particular document is available from CISTI's collection of course.
The first few links of this query provide some examples - and Richard provides some suitable examples in his posting on SLP.
UPDATE (March 2, 2009): Apparently it's available beyond Canada.
UPDATE (March 4, 2009): The update is incorrect it seems - yea, just it's just in Canada. If you find out otherwise, let me know please?