Does Urborg, Tomb of Yawgmoth make non-land permanents tap for black mana?

Urborg, Tomb of Yawgmoth has a single static ability: "Each land is a Swamp in addition to its other land types." This ability modifies the subtype of lands only — it does not grant any ability to non-land permanents, and it does not directly grant a mana ability to anything.

The reason Swamps tap for black mana is the basic land type rule: any land with the subtype Swamp has the intrinsic ability "{T}: Add {B}" (CR 305.7). This intrinsic ability is only granted to permanents that are lands with the Swamp subtype. A creature or artifact that somehow gained the Swamp subtype (without being a land) would not receive this mana ability, because the rule applies specifically to lands.

Urborg also does not turn non-land permanents into lands. It only affects permanents that are already lands. So a creature sitting on the battlefield is completely unaffected by Urborg's ability — it does not become a Swamp, and it gains no ability to tap for {B}.

Concrete example: You control a Grizzly Bears (a 2/2 creature) and an Urborg, Tomb of Yawgmoth. Urborg's ability looks at each land — Grizzly Bears is not a land, so it is ignored entirely. Grizzly Bears cannot tap for {B} and is not a Swamp.

This is a common misconception. Urborg's power lies in turning non-basic lands (like utility lands or your opponent's lands) into Swamps, not in affecting non-land permanents.