AMD has launched mobile versions of the HD 7000 series of GPUs . It includes the HD 7900M, HD 7800M and HD7700M series of GPUs .
The top end part HD 7970M uses fully enabled Puitcairn core and similar to the desktop HD 7870. With 1280 stream processors clocked at 850MHz ( compared to 1000MHz on desktop 7870 ) . The memory will remain 2GB of GDDR5 wat 4.8GHz , which will give it 153GB/s bandwidth . Going by the clocks , the 7970M should perform around 15% slower than HD 7870 .
AMD also presented some data showing their estimate of performance results for HD 7970M vs. GTX 675M .
The 7800M will have 640 stream processors clocked at 800MHz , while the HD 7700 M will have few clusters disabled , resulting in 512 cores and 32 texture units . The clocks are also lower on the HD 7700M at 675MHz . The HD 7700 will also lack PCI-E 3.0 support .
AMD slide below shows estimate of HD7870M performance vs GTX 560M ( simulated using desktop hardware ) .
Source

The top end part HD 7970M uses fully enabled Puitcairn core and similar to the desktop HD 7870. With 1280 stream processors clocked at 850MHz ( compared to 1000MHz on desktop 7870 ) . The memory will remain 2GB of GDDR5 wat 4.8GHz , which will give it 153GB/s bandwidth . Going by the clocks , the 7970M should perform around 15% slower than HD 7870 .
AMD also presented some data showing their estimate of performance results for HD 7970M vs. GTX 675M .

The 7800M will have 640 stream processors clocked at 800MHz , while the HD 7700 M will have few clusters disabled , resulting in 512 cores and 32 texture units . The clocks are also lower on the HD 7700M at 675MHz . The HD 7700 will also lack PCI-E 3.0 support .
AMD slide below shows estimate of HD7870M performance vs GTX 560M ( simulated using desktop hardware ) .

Source