vCash is virtual cash. New posters start out with $1000 in their accounts. The value is displayed behind the 'Points:' indicator on the upper right portion of your posts. Note that any vCash that is currently placed on vBets that have not yet been settled will not show in your vCash points.
Additional vCash can be earned by either donating actual cash to BP, winning contests that award vCash, and by winning vBets. Small amounts of vCash are also given for each post made on BP.
Any donation to BP gets somebody vCash for every dollar they donate to BP (10,000 per each dollar in 2009), and that amount is doubled, with an equal amount coming from BB73's account. So just a donation of $5 earns v$100,000 right from the start. And donations also earn a Donor banner for 2009, which appears to the left of where the vCash/points are displayed.
For more info on donations:
BP.Drive.2009.Thread
vCash can be wagered in something called vBets. These can be seen as actual forum threads, but they have a '$' to the left of their title in the forum list, and they also say 'vBookie' at the start of their name.
Currently open vBets can be seen in a list by clicking on 'Bookie' in the upper-right area of most screens (to the left of 'Arcade'). There are many individual game vBets (against the pointspread and over/under bets) created during the football season in the College Football and Pro Football forums. Additional vbets are created by vBookies throughout the year for all types of sporting events, and occasionally for non-sporting events.
If you have a good idea for a potential vBet on BP, please post it in this thread:
BP.vBet.Ideas
vCash was formerly used to buy team icons, but that part of BP has been disabled due to a security issue, so that's why you'll see others with team icons to the far right of their avatars, but those can no longer be acquired.
Additionally, each time a new vBet is created, every BP poster that has less than v$1.00 in their account receives a gift of v$100. So if you don't have very much vCash, it's in your best interest to go 'all in' on some vBet in order to get some free vCash when the next vBet is created.