Lenovo has introduced their new ThinkServer line that will be available for purchase at Lenovo Business Partners on september 30. In january this year we published that Lenovo would introduce servers based on System x technology. Read that story again HERE

Blades and high-end systems as well as the tower and rack servers IBM is selling now will still be sold tomorrow. With the Lenovo ThinkServer System x technology will be sold on places IBM itself is not selling at this moment.
The competitive mapping of ThinkServer versus System x is (T=Tower, R=Rack, S=Single socket, D=Dual socket): 

TS100 vs x3200 M2, TD110 vs x3400, TD110x vs x3500, RS110 vs x3250 M2 and RD120 vs x3650

Source: IBM and Lenovo Agreement, Lenovo ThinkServer, Announcement