The SX700-LPT is a SFX-L (the longer variant of the SFX form-factor) power supply with mighty 700W of power for its size, up 200W from the prior SX500-LG.
The “sneak peak” photo from SilverStone also shows a pair of PCI-E connectors on the PSU, which would be a first for an SFX/SFX-L power supply and permit the use of power hungry cards (or even Crossfire/SLI setups). As for efficiency, the image shows an 80 PLUS Platinum certification, which would also be a first for an SFX/SFX-L PSU. Cable management will be easy for existing SilverStone PSU owners as well as the new SX700-LPT uses SilverStone’s standard cable interface (and this also allows the use of their PP05-E short cable set).
No specifics on price or release just yet, only that the SX700-LPT power supply is coming “later this year”.