Firstly, the pre-WoTLK patch will be coming in the next few weeks: (source)
(here the text for ppl who can't read the link from work)
With the release of Wrath of the Lich King approaching, we wanted to provide you with some important information. In preparation for the expansion, we will be issuing a new content patch in the coming weeks. Much like the patch made available shortly before The Burning Crusade's release, this content patch is designed to bridge current game content with that of the expansion and will contain some exciting changes and additions.
We have outlined some of the larger features scheduled to release with the patch below:
New class spells and talents
Barbershops in capital cities
Zeppelin towers outside of Orgrimmar and Tirisfal Glades
Two brand-new Arenas featuring challenging new layouts, terrain hazards, and moving obstacles
Hunter pet skill revamp
New profession: Inscription
As mentioned above, this is not a comprehensive list, just some of the major highlights. We’ll post the full patch notes as soon as they’re available. Regarding Inscription, please note that all Burning Crusade players will be able to select Inscription as one of their two professions and level up to a skill level of 375 with it. Upon the release of Wrath of the Lich King, players who purchase and install the expansion will be able to continue leveling in Inscription and the other professions beyond 375.
Secondly, Arena points WILL BE WIPED OUT ONCE YOU LEVEL PAST 70, no carry over. (source)
(again here is the text for non-linking people)
We want to provide some information about the direction of the Arena system. Upon the release of Wrath of the Lich King, players will find they are still able to access the Arena system at level 70 for rated matches. Those competing in the Arenas at 70 will still be able to attain items using Arena points and rankings; however, we do not currently plan to offer new items or titles for this bracket. Players who level past 70 will have their Arena points reset to 0 and be removed from all Arena teams in the level-70 bracket.
Two new skirmish brackets (71-75, 76-80) will be available for players who wish to hone their Arena skills while leveling in Northrend. Those who reach level 80 will once again have the opportunity to create new Arena teams and play in rated matches once a new season starts. New items, titles, and end-of-season rewards will be offered to the most successful teams at level 80. Additionally, the sets released for the Arenas in Wrath of the Lich King will no longer share aesthetic similarities with tiered raiding gear. We want those equipped with the best PvP rewards and those with the best raiding sets to stand out from each other. Players at level 80 will also have the opportunity to compete in two new Arenas featuring challenging new layouts, terrain hazards, and moving obstacles.