Playing with Mounts 4th edition

[HMS Invincible]

How should I work mounts into my campaign? I have a player in my campaign who wants a mount, and I was willing let him get one. However, questions arose. How do mounts behave?
Are there still skill checks to force a mount into combat?
Do you still train mounts?
How much should I charge for upkeep of his mount?
What are good mounts to allow besides the warhorse/horse? I have to be careful here because a bad decision will ruin various planned dungeons.

I was thinking about giving him a dire boar mount because it sounds fancy like a warhorse but isn't too exotic like a griphon or something stupid like a lizard mount.

[Enlong]

Rules for mounted combat are actually in the Dungeon Master's Guide. Page 46.

[RTGoodman]

What he^ said.

Also, Adventurer's Vault has a ton of new mounts, and a few other Playgrounders and I homebrewed up a bunch HERE (http://www.giantitp.com/forums/showthread.php?p=4781825#post4781825) a while back.

[Mando Knight]

Note that the Mounted Combat feat has changed since 3.5. In 4E it grants access to the mount's special ability, which (if existent) is listed in the mount's entry. Monster Manual has most of the standard mounts, including griffons, wyverns, and warhorses. Also note that the character must be of sufficient level before he gains the mount's special ability.

[Townopolis]

Mounts are generally loot. Look up the price of any mount more powerful than a warhorse (I believe) and you will find that the list price for the mount corresponds nicely to the pricing for a certain level of item.

e.g. A hippogriff costs as much as a level 9 item.

This can be useful for figuring out how and when to allow access to certain types of mounts. Just replace an item of the appropriate level with the mount in your loot parcel.