Copy of a twitter message from the ACLU.
ACLU National @ACLU
"We thought we'd have to sue Trump today. But it turned out the order signing was an elaborate photo-op with no discernible policy outcome.5:42 PM - 4 May 2017"
Rumors said that Trump was going to sign an Executive Order on "religious freedom," which would allow religious-affiliated entities (like schools, hospitals) to refuse service based on religious objection (gay marriage, trans identity).
The ACLU was poised to file a lawsuit against Trump for government endorsement of discrimination. But the actual order Trump signed turned out to be a big nothing. All it does is ask that government agencies be a little more lenient in allowing churches to engage in politics without risking their tax-exempt status -- a rarely enforced law anyway.
An ACLU spokesman said what Trump signed "was, in essence, just a way to pander to religious conservatives." But Trump is trying to make up for his lack of legislative success by padding his list with relatively meaningless and unobjectionable EOs.