We welcome all reports of security vulnerabilities, we try to fix them quickly, and we credit the researchers - but we offer rewards only for higher-impact flaws. You can check out this page for more info:
http://www.google.com/about/appsecurity/reward-program/
In this context, phishing issues are tricky. Because many of our products simply have to do things such as displaying snippets of potentially attacker-controlled text and multimedia, we try to evaluate phishing concerns on a case-by-case basis. In essence, we ask ourselves how easy it would be to exploit a particular behavior to mount a convincing attack.
My take on this bug is that the attack vector is severely constrained in well-behaved e-mail clients; and that in badly-behaved clients, the existing exposure is already considerably worse than any incremental hazard caused by this flaw. It's valid and worth fixing - but does not quite meet the bar for the reward tiers set up for higher-impact bugs.