As far as i know they didn't do anything continuing the Roswell series at all (Which really sucks)
I think the end of season 3, really was the end of the entire thing.
And i think its pretty impossible they are going to do anything now since its been nearly 10 years since the show was over. Much to the dissapointment of many Roswell fans, because i think we would all love to know what they made of their lives aftet leaving the town.
(On a completly different note; im not watching season 1 of Roswell haha!)

I just saw all 3 seasons recently, and want to re watch them... The show was so good I can't believe it only lasted 3 seasons.

I live in Australia and I am so sure that late in year 2000 they had season 4 on Australin TV. Shiri had her hair cut to just past her shoulders and in the seasons 1 - 3 she has long hair. Also I googled season 4 and found heaps on season 4 including a online shop that sells it, it just sucks that it's out of stock.

Nope, it was cancelled after season 3, they decided to end it with a final episode. They did continue the storyline on the road in four books. I bought the first book and because they are so rare because they are after the series ended, they are really pricey. I had to pay 120$ for just the one book. Not the other 3

Btw the seaosn with Liz having short hair was the beginning of season two.