The simple answer is No there's not an accepted standard icon. Keep in mind that this is usually the case with icons and that shouldn't stop you from trying to find a suitable icon.
Probably the closest thing to a "standard blog icon" isn't an icon for a blog at all, but the RSS icon:
A great deal of users associate this with "blog" as most blogs have this logo plastered somewhere on the site. It's synonymous with blog because it's always seen with blogs even though it doesn't actually mean "blog".
A neat idea is pushed by The Blog Icon.
They're attempting to create a universal standard blog icon and it's completely free to use/edit/ect in any way you choose. Note they've basically taken the RSS icon and snuck a b in there to help suggest the idea of "blog". The similarity to the RSS icon means the meaning is less likely to be lost on your users. They have many color palettes so you can pick one that matches your site colors, but the standard RSS orange is most likely to be understood.
Don't forget you can put a little "What's this?" tooltip explaining what the icon is on hover, too.
I wouldn't recommend using the Tumblr/Wordpress/Blogger logos as a "blog icon" as that may create the impression that an item marked with that icon is explicitly from that service. They're not universal.