Not entirely. Mint only used Yodlee at the beginning, before Intuit acquired them, and that was a while ago. Even before the acquisition, they had a secret project to create a backup scraping platform because they worried that Yodlee would cut them off when the acquisition was announced.
Mint now uses an internal service (called FICDS, IIRC, but I'm no longer at Intuit) that still scrapes. That service also handles bank interactions for Quickbooks, TurboTax and Quicken, though the latter was sold off, so may be moving to something else. Additionally, that service allows the use of tokenization, which greatly reduces the chances that account credentials would leak based on a vulnerability in Mint or a rogue employee, since that team is pretty locked down and Mint, TurboTax and Quickbooks never store banking credentials.
As an aside, I wonder why Wells picked Xero to trial their API. It could have been a lot more impactful by doing a trial with Intuit, especially if they could have had it ready by tax season.
Also, here's a fun fact: For a number of years, Mint employees at Intuit could not see their own employee stock plans in Mint. Morgan Stanley's site was a Flash monstrosity that couldn't be scraped correctly. Asking them about it earned you a well-practiced eye roll.
http://money.stackexchange.com/questions/2212/how-does-mint-...