CBS and Viacom’s parting of ways means the U.S. terrestrial net is shaking up its Saturday morning kids block. Last month, the Eye signed a five-year deal with DIC Entertainment to take over programming duties from its former partner, Nickelodeon. The three-hour Nick Jr. block, which featured shows such as Dora the Explorer (averaging a 2.7 share for kids ages two to five), will be replaced in September with CBS’s Secret Saturday Morning Slumber Party.

The block will feature a live host and slumber party-themed interstitials, and age up to target six- to 11-year-old girls. It will air three hours of FCC-compliant children’s programming, half culled from DIC’s existing library and half from developing programs yet to be determined. CEO Andy Heyward says the company is still hammering out the final schedule, but it will include such girl-friendly hits as Madeline, Sabrina: The Animated Series and Strawberry Shortcake.

Heyward also confirms DIC’s developing series Horseland will launch in tandem with the new block. The 26 x half hour toon features stories inspired by the on-line community at www.horseland.com, where kids adopt, groom and play with equine friends. Two more block additions will be announced in the coming months.

As part of the deal, CBS becomes a partner in all consumer product and licensing activities for series airing in the block. And while he wouldn’t go into details about concrete plans, Heyward stresses there’s a large off-screen strategy, encompassing mobile, on-line and portable media platforms in the offing.

Meanwhile, after dropping the bombshell last month that they plan to merge assets to create a fifth national network, CBS and Warner Bros. are busy sorting out exactly where the programming chips will fall this month. Starting in September, Warner Bros.-owned channel The WB and CBS’s UPN will be replaced by The CW, a new net featuring a mix of programming from both broadcasters. The full distribution of the network is expected to exceed 95% of U.S. households. The five-hour Kids’ WB! animation block will remain intact and air in its Saturday morning 7 a.m. to noon slot on the new net.