It's always nice to maintain contact with places you have an interest in working. However, funding for positions is not worked out that far in advance at most academic institutions, and job vacancies are not typically known until someone tenders a resignation. As a result, there is little that anyone can do with the information. Heck, I'm a senior neuroICU fellow looking for a job, and several academic positions that were supposed to come available for 2012 have not, due to the economy and vagaries of intra-department politics at some institutions. Trying to plan for 3 years in the future is damn near impossible.
But, again, it's a small world and maintaining connections can't hurt.
