In essence, Check Point is enabling FW1 to be a termination point for SSL tunnels. The secure connection in this scenario builds on the fact that most clients can take advantage of SSL sessions for HTTP and in the future for other TCP protocols such as POP3 and SMTP.
The idea behind clientless VPNs is that you are able to access some resource via a secure connection that is already built into the client machine.
As of FP3, Check Point is promoting what they term as clientless VPNs as part of FW1.