According to the wiki page of Eletania this carries over to ME2. Does it have any effect in the later games?
According to the Mass Effect Wiki the event is flagged in save-game imports from ME1->ME2. However, there is no mention of it actually having an effect on either game.
Finding and unlocking the ruin is flagged as an event when imported into a Mass Effect 2 character, though it is currently not known whether there is any effect in the game. It is possible the import was meant to carry over to Mass Effect 3 through Mass Effect 2.
I personally haven't noticed any follow-up. I did receive the vision on Eletania, and have played through the entire Trilogy - though I haven't played any DLCs for ME3 yet.
again from the wiki, about the trinket:
If you completed Citadel: Xeltan's Complaint before coming to her, Sha'ira will give you a bonus reward, a small trinket that appears to be of Prothean design. This can be used on Eletania, a planet in the Hercules system of the Attican Beta cluster. Use the trinket when examining the anomaly at the ruins, and you will experience a short burst of information about the Protheans studying cavemen on Earth. If you do not speak to Xeltan before coming to Sha'ira, her door will be locked and you won't get the trinket.
This item was intended to be carried over in ME2 for a quest that was cut out from the game (source of this: a couple of posts in the bioware forums. yet, I think it's just rumors/voices running around, but it's the answer with the most sense I could find)
Other rumors (unverified, again from the forums) about ME3: it's the key for
or it just gives you a slight increase in your war assets.