What dyes are now available in Minecraft?

Solution 1:

Dyes made from items

• Yellow flower → Dandelion Yellow
• Red flower → Rose Red
• Cactus → Cactus Green (Cook in furnace)
• Bone → Bone Meal (white dye)

Items usable as dye

• Squid → Ink Sack (black dye)
• Lapis Lazuli Ore → Lapis Lazuli (blue dye)
• Dungeon Chest → Cocoa Beans (brown dye)

Dyes made by combining other dyes

• Rose Red + Dandelion Yellow → Orange Dye
• Bone Meal + Rose Red → Pink Dye
• Ink Sack + Bone Meal → Dark Grey Dye
• Dark Grey Dye + Bone Meal → Light Grey Dye
• Ink Sack + Bone Meal x2 → Light Grey Dye
• Cactus Green + Lapis Lazuli → Cyan Dye
• Rose Red + Lapis Lazuli → Purple Dye
• Lapis Lazuli Dye + Bone Meal → Light Blue Dye
• Cactus Green Dye + Bone Meal → Lime Green Dye
• Pink Dye + Purple Dye → Magenta Dye

Solution 2:

As always, the minecraft wiki has the answer:

http://www.minecraftwiki.net/wiki/Wool_Dyes