On the remote chance that Jane Fonda didn't realize how loved she is, her private 70th birthday celebration at the Biltmore in Midtown Thursday night served as a testament to the significant place she holds in the hearts of friends, family and even a certain ex-hubby. Poets, politicos, playwrights, fellow Oscar winners, stepchildren, co-stars and TV execs all flew in for the celebration, an unprecedented $2.4 million fund-raiser for Fonda's Georgia Campaign for Adolescent Pregnancy Prevention.