"Five years ago, the dollars changed hands and year-long commitments were made" around the time of the Upfronts each spring, says Alan Gould, founder and co-C.E.O. of IAG Research, a firm that measures the effectiveness of advertising and product placement on television.

Now that advertisers have so many more avenues open for reaching consumers, Gould adds, "the Upfront is the beginning of the negotiation" over ad rates, not the end.

Gould is quick to point out that none of this means the networks stand to lose ad revenue this year. But advertisers are going to be more selective on how they spend. Instead of plowing their budgets into traditional slots between prime-time programs, they are more and more conscious of reaching targeted and valuable—not necessarily large—audiences. These targeted viewers will have precisely the lifestyle and spending habits advertisers want.

In response, advertisers are experimenting outside of TV with increased use of the internet for search and branding, more sophisticated in-store advertising, display stations, coupons, and targeted online and mobile ads.

Meanwhile, new television strategies like product placement and one-sponsor shows and movies have become popular.

Viewer retention during ad breaks—long a weak point and newly tenuous since the advent of TiVo and other D.V.R.'s—is being encouraged with restructured ad "pods." These include shorter ad breaks, and breaks that consist only of one type of ad—say, funny ones.

Both TBS and MTV have tried the strategy. It's too soon to tell if it will, as planned, condition viewers to associate funny ads with a particular show and lead them to tune in again next week.

"Media buyers and advertisers are looking at a brave new world, and not just television," says Gould. Nevertheless, he anticipates "extraordinary interest" from advertisers in the programming announced next week.

Just don't expect The Who.