Well they made two Princess Diaries movies (which, if you've read the series, are no where NEAR as good as the books.) The first one's okay but don't watch the second one.
There was a tv series, called 1800-Where-Are-You based on the 'Missing' series.
At the moment, Avalon High has been optioned by the Disney Channel for a made-for-tv movie but production hasn't yet begun.
Meg's adult series Queen of Babble is being made into a feature film by Sharp Independent and rumour has it that Kristen Bell is playing the lead. It's supposed to hit cinemas in 2011.
How to be Popular has been optioned by MTV
The Mediator is with producer Julia Pistor
The Heather Wells Mysteries series and Jinx are with ABC
How exciting is this! I don't know when they're coming out, but after so long of wanting Meg's books to be made into movies it's FINALLY HAPPENING! I hope you're just as excited as I am!
*screams*