I was involved in an accident about 2 months ago (December 1st, 2010). I received a letter from the other parties insurance company, dated January 20th, asking for my insurance information/policy number and to fill out a report that they attached.

The damage was minor and weather related (downed powerline got caught on his vehicle and he stopped, as I avoided the debris I hit him - police were on scene but told us they were not planning on filing a report), and this is the first time I've been contacted about the accident. Don't insurance companies/agencies have a certain period they are required to contact me in? It seems to me like 2 months is horribly excessive - what am I responsible for and how do I go from here?

Did you report the accident to your insurance company? If not do so now because the other guys company will be doing just that. It is likely the two companies will work this out but you will be found at fault so ask your insurance company if there is any consequence to this like increased rates or cancellation