realmaverick - 9:37 pm on Jun 12, 2012 (gmt 0) [edited by: realmaverick at 10:20 pm (utc) on Jun 12, 2012]
The last time Matt Cutts was asked about this, he said spelling and grammar aren't currently ranking factors. However he also stated that in his experience, good blogs have good spelling, therefore it wouldn't be unreasonable to use it as a ranking factor in the future.
Assuming they did, one would hope they're smart enough to distinguish between content and user generated content such as comments on a blog post.
[edited by: realmaverick at 10:20 pm (utc) on Jun 12, 2012]