It's a little hard to verify the legitimacy of whether this particular HSBC hack is completely real because theres not enough evidence beyond some screenshots. That said though, Unu has been pretty reliable in the past on identifying SQL Injection vulnerable sites - so it looks probable.

Even though it appears that extensive access to the database server files are possible, there's something much worse... Unu has presented a screen shot of user credentials along with their login passwords.

Oh, and a cursory inspection of the (poorly) obfuscated screenshot from Unu also indicates that there's no rigor on password selection or enforcement.
What more could go wrong?
Lets hope that Unu alerted HSBC in advance of his posting and that the SQL Injection vulnerability has been fixed. It'll probably take a little longer to fix the password problems though.
Unu's blog of his most recent HSBC Bank France finding is here.