eBay is introducing a new, optional feature that allows sellers to connect with other eBay sellers to cross-promote each other's items. With the Cross-Promotion Connections feature, sellers can request a connection with any seller they know and trust, and have full control over whether to accept any requests sent to them.

Once a buyer makes a purchase, they will first see promotions for the seller's other items in places such as the Bid or BIN Confirmation page and the closed item page. And now, in a separate section, they will also see up to 5 items from sellers in that seller's connection network. This separate section will only display if a seller has added other eBay sellers to their connection network.

The new feature is managed within the My Account section of My eBay. If sellers don't wish to receive any requests from other members, they can opt-out within Preferences in My eBay.
http://www2.ebay.com/aw/core/200508221351372.html

eBay also said it is introducing enhancements that will make it easier for buyers to save and search through listings from their Favorite Sellers or Stores. With these enhancements users will be able to increase the maximum number of Favorite Sellers from 30 to 100, and limit searching to Favorite Sellers using an advanced search filter.
http://www2.ebay.com/aw/core/200508221538432.html