As MH. pointed out in this question, one no longer needs to include GoogleAdMobAdsSdk-x.x.x.jar in their Android project if they include Google Play Services (see the migrat
You can use Google Play Services v12 which does not include the overlapping namespaces. It can be downloaded using the Android's SDK Manager under "Extras" -> "Google Play Services for Froyo". This version will co-exist with AdMob stand alone SDK.
Over time Google will probably deprecate both.
Update: Google has announced the deprecation of the stand alone AdMob SDK, you must move to Google Play SDK:
On August 1, 2014, Google Play will stop accepting new or updated apps that use the old standalone Google Mobile Ads SDK v6.4.1 or lower. You must upgrade to the Google Play version of the Mobile Ads SDK by then.