The Tree of Life is available in World of Warcraft: Cataclysm beta 13189. According to Naturesgods (Tomgodfrey), Druids now can cast Regrowth instantly in Tree of Life form, cast Lifebloom on unlimited targets, and Wild Growth can be cast on 7 players at the same time rather than 5.
Recently, Ghostwalker mentioned that druids have the option to keep the classic Treant model through the Minor Glyph: The Treant.