Leaving postdoc after less than one year with no reference letter I've been in my first postdoc for a year and feel that I'm not progressing in my career. There has been communication issues with my PI, he's not very supportive of his senior postdocs, and it takes a long time to publish. 

I am currently looking for new positions, however how do I address the issue of my one year postdoc, especially if I won't be receiving a reference letter from the PI? 

Should I address this in the cover letter? 

Also, he is quite big in the field, so are there any considerations I should be careful about, for instance applying to people he has worked with? 

Would it be worthwhile to ask other PIs in the department that I have not worked with but I have been on good terms with for a reference letter?
I would apply to new postdocs using the professors at your former doctoral program as references. If there's someone at the postdoc school that you worked with and can speak positively, you could use one of them instead of one of your former profs, but I'd keep the ratio 2:1 or 3:1 in favor of your former professors.

The good thing is that you're in your first year of the postdoc. Sometimes there are just fit issues -- in terms of personalities or research topics or both. Everyone in academia is aware of this and we're aware it's not always the fault of the applicant -- especially when it comes to "big names" (== big egos). I think you could apply to new post docs referring very briefly and obliquely to fit -- and using the materials and references from your doctoral program.