last year i raced long between the beginning of march through mid-august: marathon distance or longer (up to 70 miles), usually spaced three weeks apart, but only two weeks apart on one occasion. (note that most of these races were on trails, which don't beat me up nearly the way that roads do.)
my primary observation is that i have it ready to go again in three weeks, but not after only two (although i did win that two-weeker, along with several of the others -- if i recall correctly, i won four of the races, set a masters course record in another, and won my age group in two more (i'm female and was 47 during this period), my point being that it is possible to race often and recover reasonably). alan's expectations sound appropriate. i also recommend holding off on preregistering, and, if you do the half, take it as it comes and don't be surprised/disappointed if you don't quite have the umph you hope for -- but, hey, you never know.
note that i'm not planning on keeping such a tight schedule this year, since i had to spend too many weeks either recovering or tapering to have enough time to be out playing in the woods or attending to more structured training.