On A Side Note: As you might assume, celebs get their pick of bags often long before said items are available to the general public. While many of the below items are in stores now, certain items and fabrics are not currently available.
Yves Saint Laurent Downtown Medium Tote, in red patent leather. Check YSL for worldwide boutiques or get the tote in black leather at Saks now ($1495, Saks Fifth Avenue ).
Anya Hindmarch I'm Not A Plastic Bag, in cream cotton. This bag has been hugely popular in the UK, where it sold out in only two hours. While it's out of stock online and hasn't been available yet in the US, we know that Anya Hindmarch stores are currently taking orders for delivery. The bag will be available this June ($15, Anya Hindmarch for boutiques).
UPDATE: A little bird told us that the bag will also be available at the always fantastic Ron Herman (both in stores and online, ronherman.com) this June.
Chloe Quilted Bay Shoulder Bag, in chocolate brown leather. Check Chloe.com for worldwide boutiques or get the shoulder bag in ivory white at Neimans now ($1780, Neiman Marcus). If you can live without owning this bag, check out BagBorrowOrSteal.com for a loaner.
Gucci Indy Medium Top Handle, in black leather with metal plate details. Bergdorf Goodman's website has this bag in stock now ($1890, Bergdorf Goodman).
Tod's T Bag Media in black leather. eLuxury has the bag in stock now ($1350, eLuxury.com).
Boyy Franky Bag in washed black ($575, BoyyBag.com). While currently available in five other colors, the black version will not ship for 2-4 weeks (according to the site), so order now.
Photo of Ashlee and Lindsay, courtesy of www.x17online.com, Photos of Chloe and Sienna, courtesy of www.infgoff.com.