Depending on how the break-up went it is possible to have an ex at a wedding. It shows a very special level of maturity on the part of both individuals.
Clark had reached that level of maturity, he was/is completely secure in his relationship with Lois. Whereas Lana heard about his upcoming nupitals and *pushed* to be invited. Who knows what havoc she might have caused if she did show up? Also, most of the time people like that bring along a 'date' to show the ex someone loves them. Something I am surprised she did not do here. If she had, no doubt Ellen would have been right to send Lana to the sewage plant!
