Facebook has finalized their list of accepted ad networks for use within Facebook Apps. Google AdSense is omitted from the list, meaning their use is a breach of Facebooks TOS.
Accepted As providers are (at present):
ad:C media
Ad4Game
Adap.tv
Adconion Media Group
AdJug
Adknowledge – (Cubics and Super Rewards)
Admeld
Adperio
ADTELLIGENCE
Advertising.com
Alfy Video Network
Applifier
APP Prizes
appssavvy
BannerConnect
Bizmey
Blue Noodle
BrightRoll
Casale Media
ClickForce
CPX Interactive
Criteo
DoubleDing
DSNR Media Innovations (DMI)
EpicSocial
Fox Networks
Harren Media
Httpool
igapi by Social Game Universe
IndieClick
Intergi
Jun Group
Lifestreet Media
Live Gamer
MakeMeReach
Malepar
MATOMY
Mediastay
MediaWhiz
Nabbr
One iota
Open Inventory media
Paymentwall
Peanut Labs
PubMatic
RadiumOne
RockYou
Rubicon Project
Sharethrough
smartclip
Smowtion
Social Games Ad Network – SGA
SocialVideoBytes
Sometrics
Specific Media
SponsorPay
SpotXchange
SupersonicAds
SVnetwork
Tapjoy
TokenAds
TrialPay
Underdog Media
Unruly Media
ValueClick
WildTangent
XTEND
Ybrant Digital
Facebook TOS for Advertising Providers: http://developers.facebook.com/ad_provider_terms