Today kicks off that magical week when the major broadcast networks start unveiling their fall lineups for advertisers and the excitement in the air is as thick as water! The recession, folks say, is causing advertisers to be a little stingier with the pursestrings. Meanwhile, the major networks’ share of viewers continues to decline and networks are less and less likely to invest in conventional, expensive shows. The biggest symbol of that is over at NBC, where next fall Jay Leno will headline a talk-comedy series EVERY WEEKNIGHT at 10 p.m. (9 p.m. Central). This is a real crapshoot on NBC’s part, except it isn’t, really, because Leno’s show is cheap to produce and if it fails there won’t be a huge loss. It probably won’t fail, by the way — worst-case scenario is that it’ll be cut back to one or two nights a week. What else is there to look forward to this fall? We’ll know in the next few days — stay tuned.